diff --git a/.ncrunch/Avalonia.Generators.Tests.v3.ncrunchproject b/.ncrunch/Avalonia.Generators.Tests.v3.ncrunchproject
new file mode 100644
index 0000000000..319cd523ce
--- /dev/null
+++ b/.ncrunch/Avalonia.Generators.Tests.v3.ncrunchproject
@@ -0,0 +1,5 @@
+<ProjectConfiguration>
+  <Settings>
+    <IgnoreThisComponentCompletely>True</IgnoreThisComponentCompletely>
+  </Settings>
+</ProjectConfiguration>
\ No newline at end of file
diff --git a/.ncrunch/Generators.Sandbox.v3.ncrunchproject b/.ncrunch/Generators.Sandbox.v3.ncrunchproject
new file mode 100644
index 0000000000..319cd523ce
--- /dev/null
+++ b/.ncrunch/Generators.Sandbox.v3.ncrunchproject
@@ -0,0 +1,5 @@
+<ProjectConfiguration>
+  <Settings>
+    <IgnoreThisComponentCompletely>True</IgnoreThisComponentCompletely>
+  </Settings>
+</ProjectConfiguration>
\ No newline at end of file
diff --git a/native/Avalonia.Native/src/OSX/WindowImpl.mm b/native/Avalonia.Native/src/OSX/WindowImpl.mm
index 104611eabc..925880534a 100644
--- a/native/Avalonia.Native/src/OSX/WindowImpl.mm
+++ b/native/Avalonia.Native/src/OSX/WindowImpl.mm
@@ -281,10 +281,13 @@ HRESULT WindowImpl::SetDecorations(SystemDecorations value) {
 
             case SystemDecorationsFull:
                 [Window setHasShadow:YES];
-                [Window setTitleVisibility:NSWindowTitleVisible];
-                [Window setTitlebarAppearsTransparent:NO];
                 [Window setTitle:_lastTitle];
 
+                if (!_isClientAreaExtended) {
+                    [Window setTitleVisibility:NSWindowTitleVisible];
+                    [Window setTitlebarAppearsTransparent:NO];
+                }
+
                 if (currentWindowState == Maximized) {
                     auto newFrame = [Window contentRectForFrameRect:[Window frame]].size;
 
@@ -611,7 +614,8 @@ void WindowImpl::UpdateStyle() {
     }
 
     bool wantsChrome = (_extendClientHints & AvnSystemChrome) || (_extendClientHints & AvnPreferSystemChrome);
-    bool hasTrafficLights = _isClientAreaExtended ? wantsChrome : _decorations == SystemDecorationsFull;
+    bool hasTrafficLights = (_decorations == SystemDecorationsFull) &&
+        (_isClientAreaExtended ? wantsChrome : true);
     
     NSButton* closeButton = [Window standardWindowButton:NSWindowCloseButton];
     NSButton* miniaturizeButton = [Window standardWindowButton:NSWindowMiniaturizeButton];
diff --git a/samples/ControlCatalog/MainView.xaml b/samples/ControlCatalog/MainView.xaml
index 3681298a72..9f06525821 100644
--- a/samples/ControlCatalog/MainView.xaml
+++ b/samples/ControlCatalog/MainView.xaml
@@ -241,7 +241,7 @@
               </ComboBox.Items>
             </ComboBox>
             <ComboBox HorizontalAlignment="Stretch"
-                      Items="{Binding WindowStates}"
+                      ItemsSource="{Binding WindowStates}"
                       SelectedItem="{Binding WindowState}" />
           </StackPanel>
         </Flyout>
diff --git a/samples/ControlCatalog/Pages/ClipboardPage.xaml.cs b/samples/ControlCatalog/Pages/ClipboardPage.xaml.cs
index ef3d2bbafa..b6b2ac7181 100644
--- a/samples/ControlCatalog/Pages/ClipboardPage.xaml.cs
+++ b/samples/ControlCatalog/Pages/ClipboardPage.xaml.cs
@@ -1,16 +1,23 @@
 using System;
 using System.Collections.Generic;
-
+using System.Linq;
 using Avalonia;
 using Avalonia.Controls;
+using Avalonia.Controls.Notifications;
 using Avalonia.Input;
 using Avalonia.Interactivity;
 using Avalonia.Markup.Xaml;
+using Avalonia.Platform;
+using Avalonia.Platform.Storage;
+using Avalonia.Platform.Storage.FileIO;
 
 namespace ControlCatalog.Pages
 {
     public partial class ClipboardPage : UserControl
     {
+        private INotificationManager? _notificationManager;
+        private INotificationManager NotificationManager => _notificationManager
+            ??= new WindowNotificationManager(TopLevel.GetTopLevel(this)!);
         public ClipboardPage()
         {
             InitializeComponent();
@@ -31,7 +38,7 @@ namespace ControlCatalog.Pages
 
         private async void PasteText(object? sender, RoutedEventArgs args)
         {
-            if(Application.Current!.Clipboard is { } clipboard)
+            if (Application.Current!.Clipboard is { } clipboard)
             {
                 ClipboardContent.Text = await clipboard.GetTextAsync();
             }
@@ -59,15 +66,45 @@ namespace ControlCatalog.Pages
         {
             if (Application.Current!.Clipboard is { } clipboard)
             {
-                var files = (ClipboardContent.Text ?? String.Empty)
-                .Split(new[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries);
-                if (files.Length == 0)
+                var storageProvider = TopLevel.GetTopLevel(this)!.StorageProvider;
+                var filesPath = (ClipboardContent.Text ?? string.Empty)
+                    .Split(new[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries);
+                if (filesPath.Length == 0)
                 {
                     return;
                 }
-                var dataObject = new DataObject();
-                dataObject.Set(DataFormats.FileNames, files);
-                await clipboard.SetDataObjectAsync(dataObject);
+                List<string> invalidFile = new(filesPath.Length);
+                List<IStorageFile> files = new(filesPath.Length);
+
+                for (int i = 0; i < filesPath.Length; i++)
+                {
+                    var file = await storageProvider.TryGetFileFromPathAsync(filesPath[i]);
+                    if (file is null)
+                    {
+                        invalidFile.Add(filesPath[i]);
+                    }
+                    else
+                    {
+                        files.Add(file);
+                    }
+                }
+
+                if (invalidFile.Count > 0)
+                {
+                    NotificationManager.Show(new Notification("Warning", "There is one o more invalid path.", NotificationType.Warning));
+                }
+
+                if (files.Count > 0)
+                {
+                    var dataObject = new DataObject();
+                    dataObject.Set(DataFormats.Files, files);
+                    await clipboard.SetDataObjectAsync(dataObject);
+                    NotificationManager.Show(new Notification("Success", "Copy completated.", NotificationType.Success));
+                }
+                else
+                {
+                    NotificationManager.Show(new Notification("Warning", "Any files to copy in Clipboard.", NotificationType.Warning));
+                }
             }
         }
 
@@ -75,8 +112,9 @@ namespace ControlCatalog.Pages
         {
             if (Application.Current!.Clipboard is { } clipboard)
             {
-                var fiels = await clipboard.GetDataAsync(DataFormats.FileNames) as IEnumerable<string>;
-                ClipboardContent.Text = fiels != null ? string.Join(Environment.NewLine, fiels) : string.Empty;
+                var files = await clipboard.GetDataAsync(DataFormats.Files) as IEnumerable<Avalonia.Platform.Storage.IStorageItem>;
+
+                ClipboardContent.Text = files != null ? string.Join(Environment.NewLine, files.Select(f => f.TryGetLocalPath() ?? f.Name)) : string.Empty;
             }
         }
 
@@ -95,7 +133,7 @@ namespace ControlCatalog.Pages
             {
                 await clipboard.ClearAsync();
             }
-                
+
         }
     }
 }
diff --git a/samples/ControlCatalog/Pages/ComboBoxPage.xaml.cs b/samples/ControlCatalog/Pages/ComboBoxPage.xaml.cs
index 6d759597b5..47f97e63a3 100644
--- a/samples/ControlCatalog/Pages/ComboBoxPage.xaml.cs
+++ b/samples/ControlCatalog/Pages/ComboBoxPage.xaml.cs
@@ -18,7 +18,7 @@ namespace ControlCatalog.Pages
         {
             AvaloniaXamlLoader.Load(this);
             var fontComboBox = this.Get<ComboBox>("fontComboBox");
-            fontComboBox.Items = FontManager.Current.SystemFonts;
+            fontComboBox.ItemsSource = FontManager.Current.SystemFonts;
             fontComboBox.SelectedIndex = 0;
         }
     }
diff --git a/samples/ControlCatalog/Pages/CompositionPage.axaml.cs b/samples/ControlCatalog/Pages/CompositionPage.axaml.cs
index 8b12a2d663..0d3061f361 100644
--- a/samples/ControlCatalog/Pages/CompositionPage.axaml.cs
+++ b/samples/ControlCatalog/Pages/CompositionPage.axaml.cs
@@ -32,7 +32,7 @@ public partial class CompositionPage : UserControl
     protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
     {
         base.OnAttachedToVisualTree(e);
-        this.Get<ItemsControl>("Items").Items = CreateColorItems();
+        this.Get<ItemsControl>("Items").ItemsSource = CreateColorItems();
 
     }
 
diff --git a/samples/ControlCatalog/Pages/ContextFlyoutPage.xaml b/samples/ControlCatalog/Pages/ContextFlyoutPage.xaml
index 6ef6a202b6..cb294442d2 100644
--- a/samples/ControlCatalog/Pages/ContextFlyoutPage.xaml
+++ b/samples/ControlCatalog/Pages/ContextFlyoutPage.xaml
@@ -61,7 +61,7 @@
         <Border.Styles>
           <Style Selector="MenuFlyoutPresenter MenuItem" x:DataType="viewModels:MenuItemViewModel">
             <Setter Property="Header" Value="{Binding Header}"/>
-            <Setter Property="Items" Value="{Binding Items}"/>
+            <Setter Property="ItemsSource" Value="{Binding Items}"/>
             <Setter Property="Command" Value="{Binding Command}"/>
             <Setter Property="CommandParameter" Value="{Binding CommandParameter}"/>
           </Style>
diff --git a/samples/ControlCatalog/Pages/ContextMenuPage.xaml b/samples/ControlCatalog/Pages/ContextMenuPage.xaml
index 962f0308f7..06eba52605 100644
--- a/samples/ControlCatalog/Pages/ContextMenuPage.xaml
+++ b/samples/ControlCatalog/Pages/ContextMenuPage.xaml
@@ -51,13 +51,13 @@
         <Border.Styles>
           <Style Selector="ContextMenu MenuItem" x:DataType="viewModels:MenuItemViewModel">
             <Setter Property="Header" Value="{Binding Header}"/>
-            <Setter Property="Items" Value="{Binding Items}"/>
+            <Setter Property="ItemsSource" Value="{Binding Items}"/>
             <Setter Property="Command" Value="{Binding Command}"/>
             <Setter Property="CommandParameter" Value="{Binding CommandParameter}"/>
           </Style>
         </Border.Styles>
         <Border.ContextMenu>
-          <ContextMenu Items="{Binding MenuItems}" />
+          <ContextMenu ItemsSource="{Binding MenuItems}" />
         </Border.ContextMenu>
         <TextBlock Text="Dynamically Generated"/>
       </Border>
diff --git a/samples/ControlCatalog/Pages/CursorPage.xaml b/samples/ControlCatalog/Pages/CursorPage.xaml
index 30bad06d72..66f2b8b2e3 100644
--- a/samples/ControlCatalog/Pages/CursorPage.xaml
+++ b/samples/ControlCatalog/Pages/CursorPage.xaml
@@ -8,7 +8,7 @@
       <TextBlock Classes="h2">Defines a cursor (mouse pointer)</TextBlock>
     </StackPanel>
 
-    <ListBox Grid.Row="1" Items="{Binding StandardCursors}" Margin="0 8 8 8">
+    <ListBox Grid.Row="1" ItemsSource="{Binding StandardCursors}" Margin="0 8 8 8">
       <ListBox.Styles>
         <Style Selector="ListBoxItem">
           <Setter Property="Cursor" Value="{Binding Cursor}" x:DataType="viewModels:StandardCursorModel"/>
diff --git a/samples/ControlCatalog/Pages/CustomDrawingExampleControl.cs b/samples/ControlCatalog/Pages/CustomDrawingExampleControl.cs
index db74be7c08..549cf3d740 100644
--- a/samples/ControlCatalog/Pages/CustomDrawingExampleControl.cs
+++ b/samples/ControlCatalog/Pages/CustomDrawingExampleControl.cs
@@ -133,17 +133,17 @@ namespace ControlCatalog.Pages
 
             // 0,0 refers to the top-left of the control now. It is not prime time to draw gui stuff because it'll be under the world 
 
-            var translateModifier = context.PushPreTransform(Avalonia.Matrix.CreateTranslation(new Avalonia.Vector(halfWidth, halfHeight)));
+            var translateModifier = context.PushTransform(Avalonia.Matrix.CreateTranslation(new Avalonia.Vector(halfWidth, halfHeight)));
 
             // now 0,0 refers to the ViewportCenter(X,Y). 
             var rotationMatrix = Avalonia.Matrix.CreateRotation(Rotation);
-            var rotationModifier = context.PushPreTransform(rotationMatrix);
+            var rotationModifier = context.PushTransform(rotationMatrix);
 
             // everything is rotated but not scaled 
 
-            var scaleModifier = context.PushPreTransform(Avalonia.Matrix.CreateScale(Scale, -Scale));
+            var scaleModifier = context.PushTransform(Avalonia.Matrix.CreateScale(Scale, -Scale));
 
-            var mapPositionModifier = context.PushPreTransform(Matrix.CreateTranslation(new Vector(-ViewportCenterX, -ViewportCenterY)));
+            var mapPositionModifier = context.PushTransform(Matrix.CreateTranslation(new Vector(-ViewportCenterX, -ViewportCenterY)));
 
             // now everything is rotated and scaled, and at the right position, now we're drawing strictly in world coordinates
 
diff --git a/samples/ControlCatalog/Pages/DialogsPage.xaml.cs b/samples/ControlCatalog/Pages/DialogsPage.xaml.cs
index 02e3027aa6..971a6a6718 100644
--- a/samples/ControlCatalog/Pages/DialogsPage.xaml.cs
+++ b/samples/ControlCatalog/Pages/DialogsPage.xaml.cs
@@ -106,7 +106,7 @@ namespace ControlCatalog.Pages
                     Directory = initialDirectory,
                     InitialFileName = initialFileName
                 }.ShowAsync(GetWindow());
-                results.Items = result;
+                results.ItemsSource = result;
                 resultsVisible.IsVisible = result?.Any() == true;
             };
             this.Get<Button>("OpenMultipleFiles").Click += async delegate
@@ -118,7 +118,7 @@ namespace ControlCatalog.Pages
                     Directory = lastSelectedDirectory?.Path is {IsAbsoluteUri:true} path ? path.LocalPath : null,
                     AllowMultiple = true
                 }.ShowAsync(GetWindow());
-                results.Items = result;
+                results.ItemsSource = result;
                 resultsVisible.IsVisible = result?.Any() == true;
             };
             this.Get<Button>("SaveFile").Click += async delegate
@@ -132,7 +132,7 @@ namespace ControlCatalog.Pages
                     DefaultExtension = filters?.Any() == true ? "txt" : null,
                     InitialFileName = "test.txt"
                 }.ShowAsync(GetWindow());
-                results.Items = new[] { result };
+                results.ItemsSource = new[] { result };
                 resultsVisible.IsVisible = result != null;
             };
             this.Get<Button>("SelectFolder").Click += async delegate
@@ -149,7 +149,7 @@ namespace ControlCatalog.Pages
                 else
                 {
                     SetFolder(await GetStorageProvider().TryGetFolderFromPathAsync(result));
-                    results.Items = new[] { result };
+                    results.ItemsSource = new[] { result };
                     resultsVisible.IsVisible = true;
                 }
             };
@@ -164,7 +164,7 @@ namespace ControlCatalog.Pages
                 {
                     AllowDirectorySelection = true
                 });
-                results.Items = result;
+                results.ItemsSource = result;
                 resultsVisible.IsVisible = result?.Any() == true;
             };
             this.Get<Button>("DecoratedWindow").Click += delegate
@@ -332,7 +332,7 @@ namespace ControlCatalog.Pages
                     }
                 }
 
-                results.Items = mappedResults;
+                results.ItemsSource = mappedResults;
                 resultsVisible.IsVisible = mappedResults.Any();
             }
         }
diff --git a/samples/ControlCatalog/Pages/ListBoxPage.xaml b/samples/ControlCatalog/Pages/ListBoxPage.xaml
index b1b1b99c9c..eef81c25fa 100644
--- a/samples/ControlCatalog/Pages/ListBoxPage.xaml
+++ b/samples/ControlCatalog/Pages/ListBoxPage.xaml
@@ -30,7 +30,7 @@
       <Button Command="{Binding RemoveItemCommand}">Remove</Button>
       <Button Command="{Binding SelectRandomItemCommand}">Select Random Item</Button>
     </StackPanel>
-    <ListBox Items="{Binding Items}"
+    <ListBox ItemsSource="{Binding Items}"
              Selection="{Binding Selection}"
              DisplayMemberBinding="{Binding (viewModels:ItemModel).ID, StringFormat='{}Item {0:N0}'}"
              AutoScrollToSelectedItem="{Binding AutoScrollToSelectedItem}"
diff --git a/samples/ControlCatalog/Pages/MenuPage.xaml b/samples/ControlCatalog/Pages/MenuPage.xaml
index 6eb109874f..40476f91f7 100644
--- a/samples/ControlCatalog/Pages/MenuPage.xaml
+++ b/samples/ControlCatalog/Pages/MenuPage.xaml
@@ -45,11 +45,11 @@
 
             <StackPanel>
                 <TextBlock Classes="h3" Margin="4 8">Dyanamically generated</TextBlock>
-                <Menu Items="{Binding MenuItems}">
+                <Menu ItemsSource="{Binding MenuItems}">
                     <Menu.Styles>
                         <Style Selector="MenuItem" x:DataType="viewModels:MenuItemViewModel">
                             <Setter Property="Header" Value="{Binding Header}"/>
-                            <Setter Property="Items" Value="{Binding Items}"/>
+                            <Setter Property="ItemsSource" Value="{Binding Items}"/>
                             <Setter Property="Command" Value="{Binding Command}"/>
                             <Setter Property="CommandParameter" Value="{Binding CommandParameter}"/>
                         </Style>
@@ -68,7 +68,7 @@
                         <Separator/>
                         <MenuItem Header="Execu_te Script..." />
                         <Separator/>
-                        <MenuItem Header="_Recent" Items="{Binding RecentItems}">
+                        <MenuItem Header="_Recent" ItemsSource="{Binding RecentItems}">
                             <MenuItem.Styles>
                                 <Style Selector="MenuItem" x:DataType="viewModels:MenuItemViewModel">
                                     <Setter Property="Header" Value="{Binding Header}"/>
diff --git a/samples/ControlCatalog/Pages/NativeEmbedPage.xaml.cs b/samples/ControlCatalog/Pages/NativeEmbedPage.xaml.cs
index 83554c007d..5e6f035027 100644
--- a/samples/ControlCatalog/Pages/NativeEmbedPage.xaml.cs
+++ b/samples/ControlCatalog/Pages/NativeEmbedPage.xaml.cs
@@ -33,10 +33,10 @@ namespace ControlCatalog.Pages
         {
             new ContextMenu()
             {
-                Items = new List<MenuItem>
-            {
-                new MenuItem() { Header = "Test" }, new MenuItem() { Header = "Test" }
-            }
+                Items =
+                {
+                    new MenuItem() { Header = "Test" }, new MenuItem() { Header = "Test" }
+                }
             }.Open((Control)sender);
         }
 
diff --git a/samples/ControlCatalog/Pages/NumericUpDownPage.xaml b/samples/ControlCatalog/Pages/NumericUpDownPage.xaml
index e76787f184..51516ff0b1 100644
--- a/samples/ControlCatalog/Pages/NumericUpDownPage.xaml
+++ b/samples/ControlCatalog/Pages/NumericUpDownPage.xaml
@@ -27,7 +27,7 @@
       </Grid>
       <Grid Grid.Row="0" Grid.Column="1" Margin="8" ColumnDefinitions="Auto, 120" RowDefinitions="Auto,Auto,Auto,Auto,Auto">
         <TextBlock Grid.Row="0" Grid.Column="0" VerticalAlignment="Center" Margin="2">FormatString:</TextBlock>
-        <ComboBox Grid.Row="0" Grid.Column="1" Items="{Binding Formats}" SelectedItem="{Binding SelectedFormat}"
+        <ComboBox Grid.Row="0" Grid.Column="1" ItemsSource="{Binding Formats}" SelectedItem="{Binding SelectedFormat}"
                   VerticalAlignment="Center" Margin="2">
           <ComboBox.ItemTemplate>
             <DataTemplate>
@@ -41,11 +41,11 @@
         </ComboBox>
 
         <TextBlock Grid.Row="1" Grid.Column="0" VerticalAlignment="Center" Margin="2">ButtonSpinnerLocation:</TextBlock>
-        <ComboBox Grid.Row="1" Grid.Column="1" Items="{Binding SpinnerLocations}" SelectedItem="{Binding #upDown.ButtonSpinnerLocation}"
+        <ComboBox Grid.Row="1" Grid.Column="1" ItemsSource="{Binding SpinnerLocations}" SelectedItem="{Binding #upDown.ButtonSpinnerLocation}"
                   VerticalAlignment="Center" Margin="2"/>
 
         <TextBlock Grid.Row="2" Grid.Column="0" VerticalAlignment="Center" Margin="2">CultureInfo:</TextBlock>
-        <ComboBox x:Name="CultureSelector" Grid.Row="2" Grid.Column="1" Items="{Binding Cultures}"
+        <ComboBox x:Name="CultureSelector" Grid.Row="2" Grid.Column="1" ItemsSource="{Binding Cultures}"
                   VerticalAlignment="Center" Margin="2"/>
 
         <TextBlock Grid.Row="3" Grid.Column="0" VerticalAlignment="Center" Margin="2">Watermark:</TextBlock>
diff --git a/samples/ControlCatalog/Pages/RefreshContainerPage.axaml b/samples/ControlCatalog/Pages/RefreshContainerPage.axaml
index f3bf1724b4..f6ea26a84c 100644
--- a/samples/ControlCatalog/Pages/RefreshContainerPage.axaml
+++ b/samples/ControlCatalog/Pages/RefreshContainerPage.axaml
@@ -21,7 +21,7 @@
                       Margin="5">
       <ListBox HorizontalAlignment="Stretch"
                VerticalAlignment="Top"
-               Items="{Binding Items}"/>
+               ItemsSource="{Binding Items}"/>
     </RefreshContainer>
   </DockPanel>
 </UserControl>
diff --git a/samples/ControlCatalog/Pages/ScrollSnapPage.xaml b/samples/ControlCatalog/Pages/ScrollSnapPage.xaml
index 237822041b..fa206f0dff 100644
--- a/samples/ControlCatalog/Pages/ScrollSnapPage.xaml
+++ b/samples/ControlCatalog/Pages/ScrollSnapPage.xaml
@@ -16,14 +16,14 @@
         <StackPanel Orientation="Vertical"
                     Spacing="4">
           <TextBlock Text="Snap Point Type" />
-          <ComboBox Items="{Binding AvailableSnapPointsType}"
+          <ComboBox ItemsSource="{Binding AvailableSnapPointsType}"
                     SelectedItem="{Binding SnapPointsType}" />
         </StackPanel>
 
         <StackPanel Orientation="Vertical"
                     Spacing="4">
           <TextBlock Text="Snap Point Alignment" />
-          <ComboBox Items="{Binding AvailableSnapPointsAlignment}"
+          <ComboBox ItemsSource="{Binding AvailableSnapPointsAlignment}"
                     SelectedItem="{Binding SnapPointsAlignment}" />
         </StackPanel>
 
diff --git a/samples/ControlCatalog/Pages/ScrollViewerPage.xaml b/samples/ControlCatalog/Pages/ScrollViewerPage.xaml
index fa8714959b..1a3d61eb85 100644
--- a/samples/ControlCatalog/Pages/ScrollViewerPage.xaml
+++ b/samples/ControlCatalog/Pages/ScrollViewerPage.xaml
@@ -13,12 +13,12 @@
 
         <StackPanel Orientation="Vertical" Spacing="4">
           <TextBlock Text="Horizontal Scroll" />
-          <ComboBox Items="{Binding AvailableVisibility}" SelectedItem="{Binding HorizontalScrollVisibility}" />
+          <ComboBox ItemsSource="{Binding AvailableVisibility}" SelectedItem="{Binding HorizontalScrollVisibility}" />
         </StackPanel>
 
         <StackPanel Orientation="Vertical" Spacing="4">
           <TextBlock Text="Vertical Scroll" />
-          <ComboBox Items="{Binding AvailableVisibility}" SelectedItem="{Binding VerticalScrollVisibility}" />
+          <ComboBox ItemsSource="{Binding AvailableVisibility}" SelectedItem="{Binding VerticalScrollVisibility}" />
         </StackPanel>
       </StackPanel>
 
diff --git a/samples/ControlCatalog/Pages/TabStripPage.xaml b/samples/ControlCatalog/Pages/TabStripPage.xaml
index 533590b48d..b576beeb5f 100644
--- a/samples/ControlCatalog/Pages/TabStripPage.xaml
+++ b/samples/ControlCatalog/Pages/TabStripPage.xaml
@@ -18,7 +18,7 @@
         <Separator Margin="0 16"/>
 
         <TextBlock Classes="h1">Dynamically generated</TextBlock>
-        <TabStrip Items="{Binding Tabs}">
+        <TabStrip ItemsSource="{Binding Tabs}">
             <TabStrip.Styles>
                 <Style Selector="TabStripItem" x:DataType="viewModels:TabControlPageViewModelItem">
                     <Setter Property="IsEnabled" Value="{Binding IsEnabled}"/>
diff --git a/samples/ControlCatalog/Pages/ThemePage.axaml.cs b/samples/ControlCatalog/Pages/ThemePage.axaml.cs
index 5a0c4cba43..d355b399a4 100644
--- a/samples/ControlCatalog/Pages/ThemePage.axaml.cs
+++ b/samples/ControlCatalog/Pages/ThemePage.axaml.cs
@@ -12,7 +12,7 @@ namespace ControlCatalog.Pages
         {
             InitializeComponent();
 
-            Selector.Items = new[]
+            Selector.ItemsSource = new[]
             {
                 ThemeVariant.Default,
                 ThemeVariant.Dark,
diff --git a/samples/ControlCatalog/Pages/TransitioningContentControlPage.axaml b/samples/ControlCatalog/Pages/TransitioningContentControlPage.axaml
index 42042652e3..88f2aa68fc 100644
--- a/samples/ControlCatalog/Pages/TransitioningContentControlPage.axaml
+++ b/samples/ControlCatalog/Pages/TransitioningContentControlPage.axaml
@@ -53,7 +53,7 @@
             
             <StackPanel Margin="5" Spacing="5" Grid.IsSharedSizeScope="True">
                 <HeaderedContentControl Header="Select a transition">
-                     <ComboBox Items="{Binding PageTransitions}" SelectedItem="{Binding SelectedTransition}" />
+                     <ComboBox ItemsSource="{Binding PageTransitions}" SelectedItem="{Binding SelectedTransition}" />
                 </HeaderedContentControl>
                 <HeaderedContentControl Header="Duration">
                      <NumericUpDown Value="{Binding Duration}" Increment="250" Minimum="100" />
diff --git a/samples/ControlCatalog/Pages/TreeViewPage.xaml b/samples/ControlCatalog/Pages/TreeViewPage.xaml
index 1665a59c0a..2e3fca58cb 100644
--- a/samples/ControlCatalog/Pages/TreeViewPage.xaml
+++ b/samples/ControlCatalog/Pages/TreeViewPage.xaml
@@ -11,7 +11,7 @@
                 HorizontalAlignment="Center"
                 Spacing="16">
       <StackPanel Orientation="Vertical" Spacing="8">
-        <TreeView Items="{Binding Items}" SelectedItems="{Binding SelectedItems}" SelectionMode="{Binding SelectionMode}" Width="250" Height="350">
+        <TreeView ItemsSource="{Binding Items}" SelectedItems="{Binding SelectedItems}" SelectionMode="{Binding SelectionMode}" Width="250" Height="350">
           <TreeView.ItemTemplate>
             <TreeDataTemplate ItemsSource="{Binding Children}">
               <TextBlock Text="{Binding Header}"/>
diff --git a/samples/IntegrationTestApp/MainWindow.axaml b/samples/IntegrationTestApp/MainWindow.axaml
index d4a96c5f17..95378ed717 100644
--- a/samples/IntegrationTestApp/MainWindow.axaml
+++ b/samples/IntegrationTestApp/MainWindow.axaml
@@ -109,7 +109,7 @@
           <StackPanel DockPanel.Dock="Bottom">
             <Button Name="ListBoxSelectionClear">Clear Selection</Button>
           </StackPanel>
-          <ListBox Name="BasicListBox" Items="{Binding ListBoxItems}" SelectionMode="Multiple"/>
+          <ListBox Name="BasicListBox" ItemsSource="{Binding ListBoxItems}" SelectionMode="Multiple"/>
         </DockPanel>
       </TabItem>
       
@@ -151,6 +151,12 @@
               <ComboBoxItem Name="ShowWindowStateMaximized">Maximized</ComboBoxItem>
               <ComboBoxItem Name="ShowWindowStateFullScreen">FullScreen</ComboBoxItem>
             </ComboBox>
+            <ComboBox Name="ShowWindowSystemDecorations" SelectedIndex="2">
+              <ComboBoxItem Name="ShowWindowSystemDecorationsNone">None</ComboBoxItem>
+              <ComboBoxItem Name="ShowWindowSystemDecorationsBorderOnly">BorderOnly</ComboBoxItem>
+              <ComboBoxItem Name="ShowWindowSystemDecorationsFull">Full</ComboBoxItem>
+            </ComboBox>
+            <CheckBox Name="ShowWindowExtendClientAreaToDecorationsHint">ExtendClientAreaToDecorationsHint</CheckBox>
             <CheckBox Name="ShowWindowCanResize" IsChecked="True">Can Resize</CheckBox>
             <Button Name="ShowWindow">Show Window</Button>
             <Button Name="SendToBack">Send to Back</Button>
diff --git a/samples/IntegrationTestApp/MainWindow.axaml.cs b/samples/IntegrationTestApp/MainWindow.axaml.cs
index 19eb1d64b0..c9c7939c1c 100644
--- a/samples/IntegrationTestApp/MainWindow.axaml.cs
+++ b/samples/IntegrationTestApp/MainWindow.axaml.cs
@@ -68,6 +68,8 @@ namespace IntegrationTestApp
             var locationComboBox = this.GetControl<ComboBox>("ShowWindowLocation");
             var stateComboBox = this.GetControl<ComboBox>("ShowWindowState");
             var size = !string.IsNullOrWhiteSpace(sizeTextBox.Text) ? Size.Parse(sizeTextBox.Text) : (Size?)null;
+            var systemDecorations = this.GetControl<ComboBox>("ShowWindowSystemDecorations");
+            var extendClientArea = this.GetControl<CheckBox>("ShowWindowExtendClientAreaToDecorationsHint");
             var canResizeCheckBox = this.GetControl<CheckBox>("ShowWindowCanResize");
             var owner = (Window)this.GetVisualRoot()!;
 
@@ -95,6 +97,8 @@ namespace IntegrationTestApp
             }
 
             sizeTextBox.Text = string.Empty;
+            window.ExtendClientAreaToDecorationsHint = extendClientArea.IsChecked ?? false;
+            window.SystemDecorations = (SystemDecorations)systemDecorations.SelectedIndex;
             window.WindowState = (WindowState)stateComboBox.SelectedIndex;
 
             switch (modeComboBox.SelectedIndex)
@@ -158,7 +162,7 @@ namespace IntegrationTestApp
             var popup = new Popup
             {
                 WindowManagerAddShadowHint = false,
-                PlacementMode = PlacementMode.AnchorAndGravity,
+                Placement = PlacementMode.AnchorAndGravity,
                 PlacementAnchor = PopupAnchor.Top,
                 PlacementGravity = PopupGravity.Bottom,
                 Width= 200,
diff --git a/samples/IntegrationTestApp/ShowWindowTest.axaml b/samples/IntegrationTestApp/ShowWindowTest.axaml
index bd6910dd4d..720ff6c344 100644
--- a/samples/IntegrationTestApp/ShowWindowTest.axaml
+++ b/samples/IntegrationTestApp/ShowWindowTest.axaml
@@ -6,7 +6,7 @@
         x:DataType="Window"
         Title="Show Window Test">
   <integrationTestApp:MeasureBorder Name="MyBorder">
-    <Grid ColumnDefinitions="Auto,Auto" RowDefinitions="Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto">
+    <Grid ColumnDefinitions="Auto,Auto" RowDefinitions="Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto">
       <Label Grid.Column="0" Grid.Row="1">Client Size</Label>
       <TextBox Name="CurrentClientSize" Grid.Column="1" Grid.Row="1" IsReadOnly="True"
                Text="{Binding ClientSize, Mode=OneWay}" />
@@ -35,13 +35,25 @@
         <ComboBoxItem Name="WindowStateFullScreen">FullScreen</ComboBoxItem>
       </ComboBox>
 
-      <Label Grid.Column="0" Grid.Row="8">Order (mac)</Label>
-      <TextBox Name="CurrentOrder" Grid.Column="1" Grid.Row="8" IsReadOnly="True" />
+      <Label Grid.Column="0" Grid.Row="8">SystemDecorations</Label>
+      <ComboBox Name="CurrentSystemDecorations" Grid.Column="1" Grid.Row="8"  SelectedIndex="{Binding SystemDecorations}">
+        <ComboBoxItem Name="SystemDecorationsNone">None</ComboBoxItem>
+        <ComboBoxItem Name="SystemDecorationsBorderOnly">BorderOnly</ComboBoxItem>
+        <ComboBoxItem Name="SystemDecorationsFull">Full</ComboBoxItem>
+      </ComboBox>
+
+      <CheckBox Name="CurrentExtendClientAreaToDecorationsHint" Grid.ColumnSpan="2" Grid.Row="9"
+                IsChecked="{Binding ExtendClientAreaToDecorationsHint}">
+        ExtendClientAreaToDecorationsHint
+      </CheckBox>
+
+      <Label Grid.Column="0" Grid.Row="10">Order (mac)</Label>
+      <TextBox Name="CurrentOrder" Grid.Column="1" Grid.Row="10" IsReadOnly="True" />
       
-      <Label Grid.Row="9" Content="MeasuredWith:" />
-      <TextBlock Grid.Column="1" Grid.Row="9" Name="CurrentMeasuredWithText" Text="{Binding #MyBorder.MeasuredWith}" />
+      <Label Grid.Row="11" Content="MeasuredWith:" />
+      <TextBlock Grid.Column="1" Grid.Row="11" Name="CurrentMeasuredWithText" Text="{Binding #MyBorder.MeasuredWith}" />
 
-      <Button Name="HideButton" Grid.Row="10" Command="{Binding $parent[Window].Hide}">Hide</Button>
+      <Button Name="HideButton" Grid.Row="12" Command="{Binding $parent[Window].Hide}">Hide</Button>
       
     </Grid>
   </integrationTestApp:MeasureBorder>
diff --git a/samples/RenderDemo/Pages/RenderTargetBitmapPage.cs b/samples/RenderDemo/Pages/RenderTargetBitmapPage.cs
index b88dded39b..8d6fb15a32 100644
--- a/samples/RenderDemo/Pages/RenderTargetBitmapPage.cs
+++ b/samples/RenderDemo/Pages/RenderTargetBitmapPage.cs
@@ -29,7 +29,7 @@ namespace RenderDemo.Pages
         public override void Render(DrawingContext context)
         {
             using (var ctx = _bitmap.CreateDrawingContext())
-            using (ctx.PushPostTransform(Matrix.CreateTranslation(-100, -100)
+            using (ctx.PushTransform(Matrix.CreateTranslation(-100, -100)
                                          * Matrix.CreateRotation(_st.Elapsed.TotalSeconds)
                                          * Matrix.CreateTranslation(100, 100)))
             {
diff --git a/samples/SampleControls/HamburgerMenu/HamburgerMenu.cs b/samples/SampleControls/HamburgerMenu/HamburgerMenu.cs
index 7ff8160720..57f8a138af 100644
--- a/samples/SampleControls/HamburgerMenu/HamburgerMenu.cs
+++ b/samples/SampleControls/HamburgerMenu/HamburgerMenu.cs
@@ -57,7 +57,7 @@ namespace ControlSamples
             {
                 if (_splitView is not null && _splitView.DisplayMode == SplitViewDisplayMode.Overlay)
                 {
-                    _splitView.SetValue(SplitView.IsPaneOpenProperty, false, Avalonia.Data.BindingPriority.Animation);
+                    _splitView.SetCurrentValue(SplitView.IsPaneOpenProperty, false);
                 }
             }
         }
diff --git a/src/Avalonia.Base/CornerRadius.cs b/src/Avalonia.Base/CornerRadius.cs
index 1666fac2e1..82791999d7 100644
--- a/src/Avalonia.Base/CornerRadius.cs
+++ b/src/Avalonia.Base/CornerRadius.cs
@@ -60,15 +60,6 @@ namespace Avalonia
         /// </summary>
         public double BottomLeft { get; }
 
-        /// <summary>
-        /// Gets a value indicating whether the instance has default values (all corner radii are set to 0).
-        /// </summary>
-        public bool IsDefault => TopLeft == 0 && TopRight == 0 && BottomLeft == 0 && BottomRight == 0;
-
-        /// <inheritdoc cref="IsDefault"/>
-        [Obsolete("Use IsDefault instead.")]
-        public bool IsEmpty => IsDefault;
-
         /// <summary>
         /// Gets a value indicating whether all corner radii are equal.
         /// </summary>
diff --git a/src/Avalonia.Base/Input/GestureRecognizers/VelocityTracker.cs b/src/Avalonia.Base/Input/GestureRecognizers/VelocityTracker.cs
index ce41aa6308..20dd376aaa 100644
--- a/src/Avalonia.Base/Input/GestureRecognizers/VelocityTracker.cs
+++ b/src/Avalonia.Base/Input/GestureRecognizers/VelocityTracker.cs
@@ -180,7 +180,7 @@ namespace Avalonia.Input.GestureRecognizers
         internal Velocity GetVelocity()
         {
             var estimate = GetVelocityEstimate();
-            if (estimate == null || estimate.PixelsPerSecond.IsDefault)
+            if (estimate == null || estimate.PixelsPerSecond == default(Vector))
             {
                 return new Velocity(Vector.Zero);
             }
diff --git a/src/Avalonia.Base/Media/BoxShadow.cs b/src/Avalonia.Base/Media/BoxShadow.cs
index dd2c23f4ae..32b2f7a2fb 100644
--- a/src/Avalonia.Base/Media/BoxShadow.cs
+++ b/src/Avalonia.Base/Media/BoxShadow.cs
@@ -45,15 +45,6 @@ namespace Avalonia.Media
             }
         }
 
-        /// <summary>
-        /// Gets a value indicating whether the instance has default values.
-        /// </summary>
-        public bool IsDefault => OffsetX == 0 && OffsetY == 0 && Blur == 0 && Spread == 0;
-
-        /// <inheritdoc cref="IsDefault"/>
-        [Obsolete("Use IsDefault instead.")]
-        public bool IsEmpty => IsDefault;
-
         private readonly static char[] s_Separator = new char[] { ' ', '\t' };
 
         struct ArrayReader
@@ -89,7 +80,7 @@ namespace Avalonia.Media
         {
             var sb = StringBuilderCache.Acquire();
 
-            if (IsDefault)
+            if (this == default)
             {
                 return "none";
             }
diff --git a/src/Avalonia.Base/Media/BoxShadows.cs b/src/Avalonia.Base/Media/BoxShadows.cs
index 50ae7699dd..ca16452a96 100644
--- a/src/Avalonia.Base/Media/BoxShadows.cs
+++ b/src/Avalonia.Base/Media/BoxShadows.cs
@@ -21,7 +21,7 @@ namespace Avalonia.Media
         {
             _first = shadow;
             _list = null;
-            Count = _first.IsDefault ? 0 : 1;
+            Count = _first == default ? 0 : 1;
         }
 
         public BoxShadows(BoxShadow first, BoxShadow[] rest)
@@ -120,7 +120,7 @@ namespace Avalonia.Media
             get
             {
                 foreach(var boxShadow in this)
-                    if (!boxShadow.IsDefault && boxShadow.IsInset)
+                    if (boxShadow != default && boxShadow.IsInset)
                         return true;
                 return false;
             }
diff --git a/src/Avalonia.Base/Media/DrawingGroup.cs b/src/Avalonia.Base/Media/DrawingGroup.cs
index 5f87da9dcd..c96d2aad57 100644
--- a/src/Avalonia.Base/Media/DrawingGroup.cs
+++ b/src/Avalonia.Base/Media/DrawingGroup.cs
@@ -73,7 +73,7 @@ namespace Avalonia.Media
         {
             var bounds = GetBounds();
 
-            using (context.PushPreTransform(Transform?.Value ?? Matrix.Identity))
+            using (context.PushTransform(Transform?.Value ?? Matrix.Identity))
             using (context.PushOpacity(Opacity, bounds))
             using (ClipGeometry != null ? context.PushGeometryClip(ClipGeometry) : default)
             using (OpacityMask != null ? context.PushOpacityMask(OpacityMask, bounds) : default)
diff --git a/src/Avalonia.Base/Media/FontFamily.cs b/src/Avalonia.Base/Media/FontFamily.cs
index f4406bd010..498bcd43a0 100644
--- a/src/Avalonia.Base/Media/FontFamily.cs
+++ b/src/Avalonia.Base/Media/FontFamily.cs
@@ -79,11 +79,6 @@ namespace Avalonia.Media
         /// <remarks>Key is only used for custom fonts.</remarks>
         public FontFamilyKey? Key { get; }
 
-        /// <summary>
-        /// Returns <c>True</c> if this instance is the system's default.
-        /// </summary>
-        public bool IsDefault => Name.Equals(DefaultFontFamilyName);
-
         /// <summary>
         /// Implicit conversion of string to FontFamily
         /// </summary>
diff --git a/src/Avalonia.Base/Media/FormattedText.cs b/src/Avalonia.Base/Media/FormattedText.cs
index d4640390d7..7d204ca8cd 100644
--- a/src/Avalonia.Base/Media/FormattedText.cs
+++ b/src/Avalonia.Base/Media/FormattedText.cs
@@ -1393,10 +1393,11 @@ namespace Avalonia.Media
                 }
             }
 
-            if (accumulatedBounds?.PlatformImpl == null || accumulatedBounds.PlatformImpl.Bounds.IsDefault)
+            if (accumulatedBounds?.PlatformImpl == null ||
+                (accumulatedBounds.PlatformImpl.Bounds.Width == 0 && accumulatedBounds.PlatformImpl.Bounds.Height == 0))
             {
                 return null;
-            }            
+            }
 
             return accumulatedBounds;
         }
diff --git a/src/Avalonia.Base/Media/ImageDrawing.cs b/src/Avalonia.Base/Media/ImageDrawing.cs
index d3e5c4841b..77b1c52be0 100644
--- a/src/Avalonia.Base/Media/ImageDrawing.cs
+++ b/src/Avalonia.Base/Media/ImageDrawing.cs
@@ -42,7 +42,7 @@ namespace Avalonia.Media
             var imageSource = ImageSource;
             var rect = Rect;
 
-            if (imageSource is object && !rect.IsDefault)
+            if (imageSource is object && (rect.Width != 0 || rect.Height != 0))
             {
                 context.DrawImage(imageSource, rect);
             }
diff --git a/src/Avalonia.Base/Media/Imaging/CroppedBitmap.cs b/src/Avalonia.Base/Media/Imaging/CroppedBitmap.cs
index 8e57f9a902..8cdf5b592a 100644
--- a/src/Avalonia.Base/Media/Imaging/CroppedBitmap.cs
+++ b/src/Avalonia.Base/Media/Imaging/CroppedBitmap.cs
@@ -77,7 +77,7 @@ namespace Avalonia.Media.Imaging
             {
                 if (Source is not IBitmap bmp)
                     return default;
-                if (SourceRect.IsDefault)
+                if (SourceRect.Width == 0 && SourceRect.Height == 0)
                     return Source.Size;
                 return SourceRect.Size.ToSizeWithDpi(bmp.Dpi);
             }
diff --git a/src/Avalonia.Base/Metadata/InheritDataTypeFromItemsAttribute.cs b/src/Avalonia.Base/Metadata/InheritDataTypeFromItemsAttribute.cs
index fac8cd8737..e9bd6ab89f 100644
--- a/src/Avalonia.Base/Metadata/InheritDataTypeFromItemsAttribute.cs
+++ b/src/Avalonia.Base/Metadata/InheritDataTypeFromItemsAttribute.cs
@@ -9,7 +9,7 @@ namespace Avalonia.Metadata;
 /// A typical usage example is a ListBox control, where <see cref="InheritDataTypeFromItemsAttribute"/> is defined on the ItemTemplate property,
 /// allowing the template to inherit the data type from the Items collection binding. 
 /// </remarks>
-[AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = true)]
+[AttributeUsage(AttributeTargets.Property, AllowMultiple = true, Inherited = true)]
 public sealed class InheritDataTypeFromItemsAttribute : Attribute
 {
     /// <summary>
diff --git a/src/Avalonia.Base/PixelRect.cs b/src/Avalonia.Base/PixelRect.cs
index ef207a3dae..85ec1041c3 100644
--- a/src/Avalonia.Base/PixelRect.cs
+++ b/src/Avalonia.Base/PixelRect.cs
@@ -9,12 +9,6 @@ namespace Avalonia
     /// </summary>
     public readonly struct PixelRect : IEquatable<PixelRect>
     {
-        /// <summary>
-        /// An empty rectangle.
-        /// </summary>
-        [Obsolete("Use the default keyword instead.")]
-        public static readonly PixelRect Empty = default;
-
         /// <summary>
         /// Initializes a new instance of the <see cref="PixelRect"/> structure.
         /// </summary>
@@ -133,15 +127,6 @@ namespace Avalonia
         /// </summary>
         public PixelPoint Center => new PixelPoint(X + (Width / 2), Y + (Height / 2));
 
-        /// <summary>
-        /// Gets a value indicating whether the instance has default values (the rectangle is empty).
-        /// </summary>
-        public bool IsDefault => Width == 0 && Height == 0;
-
-        /// <inheritdoc cref="IsDefault"/>
-        [Obsolete("Use IsDefault instead.")]
-        public bool IsEmpty => IsDefault;
-
         /// <summary>
         /// Checks for equality between two <see cref="PixelRect"/>s.
         /// </summary>
@@ -295,11 +280,11 @@ namespace Avalonia
         /// <returns>The union.</returns>
         public PixelRect Union(PixelRect rect)
         {
-            if (IsDefault)
+            if (Width == 0 && Height == 0)
             {
                 return rect;
             }
-            else if (rect.IsDefault)
+            else if (rect.Width == 0 && rect.Height == 0)
             {
                 return this;
             }
diff --git a/src/Avalonia.Base/Platform/Storage/FileIO/StorageProviderHelpers.cs b/src/Avalonia.Base/Platform/Storage/FileIO/StorageProviderHelpers.cs
index a8cbffb417..608f924808 100644
--- a/src/Avalonia.Base/Platform/Storage/FileIO/StorageProviderHelpers.cs
+++ b/src/Avalonia.Base/Platform/Storage/FileIO/StorageProviderHelpers.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Linq;
 using System.Text;
@@ -23,7 +24,7 @@ internal static class StorageProviderHelpers
 
         return null;
     }
-    
+
     public static Uri FilePathToUri(string path)
     {
         var uriPath = new StringBuilder(path)
@@ -35,6 +36,20 @@ internal static class StorageProviderHelpers
         return new UriBuilder("file", string.Empty) { Path = uriPath }.Uri;
     }
     
+    public static bool TryFilePathToUri(string path, [NotNullWhen(true)] out Uri? uri)
+    {
+        try
+        {
+            uri = FilePathToUri(path);
+            return true;
+        }
+        catch
+        {
+            uri = null;
+            return false;
+        }
+    }
+    
     public static string NameWithExtension(string path, string? defaultExtension, FilePickerFileType? filter)
     {
         var name = Path.GetFileName(path);
diff --git a/src/Avalonia.Base/Platform/Storage/StorageProviderExtensions.cs b/src/Avalonia.Base/Platform/Storage/StorageProviderExtensions.cs
index 1febb4506a..3933d23e4f 100644
--- a/src/Avalonia.Base/Platform/Storage/StorageProviderExtensions.cs
+++ b/src/Avalonia.Base/Platform/Storage/StorageProviderExtensions.cs
@@ -16,8 +16,13 @@ public static class StorageProviderExtensions
         {
             return Task.FromResult(StorageProviderHelpers.TryCreateBclStorageItem(filePath) as IStorageFile);
         }
-        
-        return provider.TryGetFileFromPathAsync(StorageProviderHelpers.FilePathToUri(filePath));
+
+        if (StorageProviderHelpers.TryFilePathToUri(filePath, out var uri))
+        {
+            return provider.TryGetFileFromPathAsync(uri);
+        }
+
+        return Task.FromResult<IStorageFile?>(null);
     }
 
     /// <inheritdoc cref="IStorageProvider.TryGetFolderFromPathAsync"/>
@@ -29,7 +34,12 @@ public static class StorageProviderExtensions
             return Task.FromResult(StorageProviderHelpers.TryCreateBclStorageItem(folderPath) as IStorageFolder);
         }
 
-        return provider.TryGetFolderFromPathAsync(StorageProviderHelpers.FilePathToUri(folderPath));
+        if (StorageProviderHelpers.TryFilePathToUri(folderPath, out var uri))
+        {
+            return provider.TryGetFolderFromPathAsync(uri);
+        }
+
+        return Task.FromResult<IStorageFolder?>(null);
     }
 
     /// <summary>
diff --git a/src/Avalonia.Base/Point.cs b/src/Avalonia.Base/Point.cs
index 86f7adf0d1..d11596d6be 100644
--- a/src/Avalonia.Base/Point.cs
+++ b/src/Avalonia.Base/Point.cs
@@ -288,13 +288,5 @@ namespace Avalonia
             x = this._x;
             y = this._y;
         }
-
-        /// <summary>
-        /// Gets a value indicating whether the X and Y coordinates are zero.
-        /// </summary>
-        public bool IsDefault
-        {
-            get { return (_x == 0) && (_y == 0); }
-        }
     }
 }
diff --git a/src/Avalonia.Base/PropertyStore/EffectiveValue`1.cs b/src/Avalonia.Base/PropertyStore/EffectiveValue`1.cs
index 0788b39459..330034f51d 100644
--- a/src/Avalonia.Base/PropertyStore/EffectiveValue`1.cs
+++ b/src/Avalonia.Base/PropertyStore/EffectiveValue`1.cs
@@ -31,7 +31,7 @@ namespace Avalonia.PropertyStore
 
             var value = inherited is null ? _metadata.DefaultValue : inherited.Value;
 
-            if (property.HasCoercion && _metadata.CoerceValue is { } coerce)
+            if (_metadata.CoerceValue is { } coerce)
             {
                 _uncommon = new()
                 {
diff --git a/src/Avalonia.Base/Rect.cs b/src/Avalonia.Base/Rect.cs
index 49dc087933..cc030eea04 100644
--- a/src/Avalonia.Base/Rect.cs
+++ b/src/Avalonia.Base/Rect.cs
@@ -16,12 +16,6 @@ namespace Avalonia
             Animation.Animation.RegisterAnimator<RectAnimator>(prop => typeof(Rect).IsAssignableFrom(prop.PropertyType));
         }
 
-        /// <summary>
-        /// An empty rectangle.
-        /// </summary>
-        [Obsolete("Use the default keyword instead.")]
-        public static readonly Rect Empty = default;
-
         /// <summary>
         /// The X position.
         /// </summary>
@@ -170,17 +164,6 @@ namespace Avalonia
         /// </summary>
         public Point Center => new Point(_x + (_width / 2), _y + (_height / 2));
 
-        /// <summary>
-        /// Gets a value indicating whether the instance has default values (the rectangle is empty).
-        /// </summary>
-        // ReSharper disable CompareOfFloatsByEqualityOperator
-        public bool IsDefault => _width == 0 && _height == 0;
-        // ReSharper restore CompareOfFloatsByEqualityOperator
-
-        /// <inheritdoc cref="IsDefault"/>
-        [Obsolete("Use IsDefault instead.")]
-        public bool IsEmpty => IsDefault;
-
         /// <summary>
         /// Checks for equality between two <see cref="Rect"/>s.
         /// </summary>
@@ -517,19 +500,18 @@ namespace Avalonia
             return rect;
         }
 
-
-            /// <summary>
-            /// Gets the union of two rectangles.
-            /// </summary>
-            /// <param name="rect">The other rectangle.</param>
-            /// <returns>The union.</returns>
-            public Rect Union(Rect rect)
+        /// <summary>
+        /// Gets the union of two rectangles.
+        /// </summary>
+        /// <param name="rect">The other rectangle.</param>
+        /// <returns>The union.</returns>
+        public Rect Union(Rect rect)
         {
-            if (IsDefault)
+            if (Width == 0 && Height == 0)
             {
                 return rect;
             }
-            else if (rect.IsDefault)
+            else if (rect.Width == 0 && rect.Height == 0)
             {
                 return this;
             }
diff --git a/src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionTarget.cs b/src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionTarget.cs
index 977acd8470..3e88b9e77b 100644
--- a/src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionTarget.cs
+++ b/src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionTarget.cs
@@ -130,8 +130,8 @@ namespace Avalonia.Rendering.Composition.Server
             }
 
             _renderTarget ??= _compositor.CreateRenderTarget(_surfaces());
-            
-            if(_dirtyRect.IsDefault && !_redrawRequested)
+
+            if ((_dirtyRect.Width == 0 && _dirtyRect.Height == 0) && !_redrawRequested)
                 return;
 
             Revision++;
@@ -163,7 +163,7 @@ namespace Avalonia.Rendering.Composition.Server
                     _dirtyRect = new Rect(0, 0, layerSize.Width, layerSize.Height);
                 }
 
-                if (!_dirtyRect.IsDefault)
+                if (_dirtyRect.Width != 0 || _dirtyRect.Height != 0)
                 {
                     using (var context = _layer.CreateDrawingContext())
                     {
@@ -260,7 +260,7 @@ namespace Avalonia.Rendering.Composition.Server
         
         public void AddDirtyRect(Rect rect)
         {
-            if(rect.IsDefault)
+            if (rect.Width == 0 && rect.Height == 0)
                 return;
             var snapped = SnapToDevicePixels(rect, Scaling);
             DebugEvents?.RectInvalidated(rect);
@@ -275,7 +275,7 @@ namespace Avalonia.Rendering.Composition.Server
 
         public void Dispose()
         {
-            if(_disposed)
+            if (_disposed)
                 return;
             _disposed = true;
             using (_compositor.RenderInterface.EnsureCurrent())
@@ -302,7 +302,7 @@ namespace Avalonia.Rendering.Composition.Server
         {
             if (_attachedVisuals.Remove(visual) && IsEnabled)
                 visual.Deactivate();
-            if(visual.IsVisibleInFrame)
+            if (visual.IsVisibleInFrame)
                 AddDirtyRect(visual.TransformedOwnContentBounds);
         }
 
diff --git a/src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionVisual.cs b/src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionVisual.cs
index f9492d0015..6fb5ad3741 100644
--- a/src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionVisual.cs
+++ b/src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionVisual.cs
@@ -23,21 +23,20 @@ namespace Avalonia.Rendering.Composition.Server
         private bool _isBackface;
         private Rect? _transformedClipBounds;
         private Rect _combinedTransformedClipBounds;
-        
+
         protected virtual void RenderCore(CompositorDrawingContextProxy canvas, Rect currentTransformedClip)
         {
-            
         }
 
         public void Render(CompositorDrawingContextProxy canvas, Rect currentTransformedClip)
         {
-            if(Visible == false || IsVisibleInFrame == false)
+            if (Visible == false || IsVisibleInFrame == false)
                 return;
-            if(Opacity == 0)
+            if (Opacity == 0)
                 return;
 
             currentTransformedClip = currentTransformedClip.Intersect(_combinedTransformedClipBounds);
-            if(currentTransformedClip.IsDefault)
+            if (currentTransformedClip.Width == 0 && currentTransformedClip.Height == 0)
                 return;
 
             Root!.RenderedVisuals++;
@@ -61,7 +60,7 @@ namespace Avalonia.Rendering.Composition.Server
                 canvas.PushClip(Root!.SnapToDevicePixels(boundsRect));
             if (Clip != null) 
                 canvas.PushGeometryClip(Clip);
-            if(OpacityMaskBrush != null)
+            if (OpacityMaskBrush != null)
                 canvas.PushOpacityMask(OpacityMaskBrush, boundsRect);
 
             RenderCore(canvas, currentTransformedClip);
@@ -78,12 +77,12 @@ namespace Avalonia.Rendering.Composition.Server
                 canvas.PopClip();
             if (AdornedVisual != null && AdornerIsClipped)
                 canvas.PopClip();
-            if(Opacity != 1)
+            if (Opacity != 1)
                 canvas.PopOpacity();
         }
 
         protected virtual bool HandlesClipToBounds => false;
-        
+
         private ReadbackData _readback0, _readback1, _readback2;
 
         /// <summary>
@@ -98,17 +97,17 @@ namespace Avalonia.Rendering.Composition.Server
                 return ref _readback1;
             return ref _readback2;
         }
-        
+
         public Matrix4x4 CombinedTransformMatrix { get; private set; } = Matrix4x4.Identity;
         public Matrix4x4 GlobalTransformMatrix { get; private set; }
 
         public virtual void Update(ServerCompositionTarget root)
         {
-            if(Parent == null && Root == null)
+            if (Parent == null && Root == null)
                 return;
-            
+
             var wasVisible = IsVisibleInFrame;
-            
+
             // Calculate new parent-relative transform
             if (_combinedTransformDirty)
             {
@@ -122,7 +121,7 @@ namespace Avalonia.Rendering.Composition.Server
             var parentTransform = (AdornedVisual ?? Parent)?.GlobalTransformMatrix ?? Matrix4x4.Identity;
 
             var newTransform = CombinedTransformMatrix * parentTransform;
-            
+
             // Check if visual was moved and recalculate face orientation
             var positionChanged = false;
             if (GlobalTransformMatrix != newTransform)
@@ -134,23 +133,23 @@ namespace Avalonia.Rendering.Composition.Server
 
             var oldTransformedContentBounds = TransformedOwnContentBounds;
             var oldCombinedTransformedClipBounds = _combinedTransformedClipBounds;
-            
+
             if (_parent?.IsDirtyComposition == true)
             {
                 IsDirtyComposition = true;
                 _isDirtyForUpdate = true;
             }
-            
+
             var invalidateOldBounds = _isDirtyForUpdate;
             var invalidateNewBounds = _isDirtyForUpdate;
 
             GlobalTransformMatrix = newTransform;
-            
+
             var ownBounds = OwnContentBounds;
             if (ownBounds != _oldOwnContentBounds || positionChanged)
             {
                 _oldOwnContentBounds = ownBounds;
-                if (ownBounds.IsDefault)
+                if (ownBounds.Width == 0 && ownBounds.Height == 0)
                     TransformedOwnContentBounds = default;
                 else
                     TransformedOwnContentBounds =
@@ -171,16 +170,16 @@ namespace Avalonia.Rendering.Composition.Server
                 AdornedVisual?._combinedTransformedClipBounds
                 ?? Parent?._combinedTransformedClipBounds
                 ?? new Rect(Root!.Size);
-            
+
             if (_transformedClipBounds != null)
                 _combinedTransformedClipBounds = _combinedTransformedClipBounds.Intersect(_transformedClipBounds.Value);
-            
+
             EffectiveOpacity = Opacity * (Parent?.EffectiveOpacity ?? 1);
 
             IsHitTestVisibleInFrame = _parent?.IsHitTestVisibleInFrame != false
                                       && Visible
                                       && !_isBackface
-                                      && !_combinedTransformedClipBounds.IsDefault;
+                                      && (_combinedTransformedClipBounds.Width != 0 || _combinedTransformedClipBounds.Height != 0);
 
             IsVisibleInFrame = IsHitTestVisibleInFrame
                                && _parent?.IsVisibleInFrame != false
@@ -213,11 +212,11 @@ namespace Avalonia.Rendering.Composition.Server
 
         void AddDirtyRect(Rect rc)
         {
-            if(rc == default)
+            if (rc == default)
                 return;
             Root?.AddDirtyRect(rc);
         }
-        
+
         /// <summary>
         /// Data that can be read from the UI thread
         /// </summary>
@@ -228,7 +227,7 @@ namespace Avalonia.Rendering.Composition.Server
             public long TargetId;
             public bool Visible;
         }
-        
+
         partial void DeserializeChangesExtra(BatchStreamReader c)
         {
             ValuesInvalidated();
@@ -245,9 +244,8 @@ namespace Avalonia.Rendering.Composition.Server
 
         protected virtual void OnDetachedFromRoot(ServerCompositionTarget target)
         {
-            
         }
-        
+
         partial void OnRootChanged()
         {
             if (Root != null)
@@ -256,12 +254,11 @@ namespace Avalonia.Rendering.Composition.Server
                 OnAttachedToRoot(Root);
             }
         }
-        
+
         protected virtual void OnAttachedToRoot(ServerCompositionTarget target)
         {
-            
         }
-        
+
         protected override void ValuesInvalidated()
         {
             _isDirtyForUpdate = true;
@@ -274,6 +271,4 @@ namespace Avalonia.Rendering.Composition.Server
         public Rect TransformedOwnContentBounds { get; set; }
         public virtual Rect OwnContentBounds => new Rect(0, 0, Size.X, Size.Y);
     }
-
-
 }
diff --git a/src/Avalonia.Base/Rendering/DirtyRects.cs b/src/Avalonia.Base/Rendering/DirtyRects.cs
index 723fe400b3..610163191d 100644
--- a/src/Avalonia.Base/Rendering/DirtyRects.cs
+++ b/src/Avalonia.Base/Rendering/DirtyRects.cs
@@ -30,7 +30,7 @@ namespace Avalonia.Rendering
         /// </remarks>
         public void Add(Rect rect)
         {
-            if (!rect.IsDefault)
+            if (rect.Width != 0 || rect.Height != 0)
             {
                 for (var i = 0; i < _rects.Count; ++i)
                 {
diff --git a/src/Avalonia.Base/Rendering/ImmediateRenderer.cs b/src/Avalonia.Base/Rendering/ImmediateRenderer.cs
index 4a12e78817..9b7d358b1d 100644
--- a/src/Avalonia.Base/Rendering/ImmediateRenderer.cs
+++ b/src/Avalonia.Base/Rendering/ImmediateRenderer.cs
@@ -83,7 +83,7 @@ namespace Avalonia.Rendering
                     }
                 }
 
-                using (context.PushPostTransform(m))
+                using (context.PushTransform(m))
                 using (context.PushOpacity(opacity, bounds))
                 using (clipToBounds
 #pragma warning disable CS0618 // Type or member is obsolete
@@ -95,7 +95,7 @@ namespace Avalonia.Rendering
 
                 using (visual.Clip != null ? context.PushGeometryClip(visual.Clip) : default)
                 using (visual.OpacityMask != null ? context.PushOpacityMask(visual.OpacityMask, bounds) : default)
-                using (context.PushTransformContainer())
+                using (context.PushTransform(Matrix.Identity))
                 {
                     visual.Render(context);
                     
diff --git a/src/Avalonia.Base/Size.cs b/src/Avalonia.Base/Size.cs
index aec237afae..7781aec607 100644
--- a/src/Avalonia.Base/Size.cs
+++ b/src/Avalonia.Base/Size.cs
@@ -27,12 +27,6 @@ namespace Avalonia
         /// </summary>
         public static readonly Size Infinity = new Size(double.PositiveInfinity, double.PositiveInfinity);
 
-        /// <summary>
-        /// A size representing zero.
-        /// </summary>
-        [Obsolete("Use the default keyword instead.")]
-        public static readonly Size Empty = new Size(0, 0);
-
         /// <summary>
         /// The width.
         /// </summary>
@@ -306,10 +300,5 @@ namespace Avalonia
             width = this._width;
             height = this._height;
         }
-
-        /// <summary>
-        /// Gets a value indicating whether the Width and Height values are zero.
-        /// </summary>
-        public bool IsDefault => (_width == 0) && (_height == 0);
     }
 }
diff --git a/src/Avalonia.Base/StyledProperty.cs b/src/Avalonia.Base/StyledProperty.cs
index dfe5a44f1b..e1b88cde49 100644
--- a/src/Avalonia.Base/StyledProperty.cs
+++ b/src/Avalonia.Base/StyledProperty.cs
@@ -34,7 +34,6 @@ namespace Avalonia
         {
             Inherits = inherits;
             ValidateValue = validate;
-            HasCoercion |= metadata.CoerceValue != null;
 
             if (validate?.Invoke(metadata.DefaultValue) == false)
             {
@@ -48,12 +47,6 @@ namespace Avalonia
         /// </summary>
         public Func<TValue, bool>? ValidateValue { get; }
 
-        /// <summary>
-        /// Gets a value indicating whether this property has any value coercion callbacks defined
-        /// in its metadata.
-        /// </summary>
-        internal bool HasCoercion { get; private set; }
-
         /// <summary>
         /// Registers the property on another type.
         /// </summary>
@@ -130,10 +123,7 @@ namespace Avalonia
         /// </summary>
         /// <typeparam name="T">The type.</typeparam>
         /// <param name="metadata">The metadata.</param>
-        public void OverrideMetadata<T>(StyledPropertyMetadata<TValue> metadata) where T : AvaloniaObject
-        {
-            base.OverrideMetadata(typeof(T), metadata);
-        }
+        public void OverrideMetadata<T>(StyledPropertyMetadata<TValue> metadata) where T : AvaloniaObject => OverrideMetadata(typeof(T), metadata);
 
         /// <summary>
         /// Overrides the metadata for the property on the specified type.
@@ -151,8 +141,6 @@ namespace Avalonia
                 }
             }
 
-            HasCoercion |= metadata.CoerceValue != null;
-
             base.OverrideMetadata(type, metadata);
         }
 
diff --git a/src/Avalonia.Base/Thickness.cs b/src/Avalonia.Base/Thickness.cs
index f9e4355edd..9513d04782 100644
--- a/src/Avalonia.Base/Thickness.cs
+++ b/src/Avalonia.Base/Thickness.cs
@@ -97,10 +97,6 @@ namespace Avalonia
         /// </summary>
         public double Bottom => _bottom;
 
-        /// <inheritdoc cref="IsDefault"/>
-        [Obsolete("Use IsDefault instead.")]
-        public bool IsEmpty => IsDefault;
-
         /// <summary>
         /// Gets a value indicating whether all sides are equal.
         /// </summary>
@@ -293,11 +289,5 @@ namespace Avalonia
             right = this._right;
             bottom = this._bottom;
         }
-
-        /// <summary>
-        /// Gets a value indicating whether the instance has default values
-        /// (the left, top, right and bottom values are zero).
-        /// </summary>
-        public bool IsDefault => (_left == 0) && (_top == 0) && (_right == 0) && (_bottom == 0);
     }
 }
diff --git a/src/Avalonia.Base/Vector.cs b/src/Avalonia.Base/Vector.cs
index 810530066f..085f043627 100644
--- a/src/Avalonia.Base/Vector.cs
+++ b/src/Avalonia.Base/Vector.cs
@@ -360,13 +360,5 @@ namespace Avalonia
             x = this._x;
             y = this._y;
         }
-
-        /// <summary>
-        /// Gets a value indicating whether the X and Y components are zero.
-        /// </summary>
-        public bool IsDefault
-        {
-            get { return (_x == 0) && (_y == 0); }
-        }
     }
 }
diff --git a/src/Avalonia.Controls.ColorPicker/Themes/Fluent/ColorPicker.xaml b/src/Avalonia.Controls.ColorPicker/Themes/Fluent/ColorPicker.xaml
index 8f52b059f1..807e4de0b1 100644
--- a/src/Avalonia.Controls.ColorPicker/Themes/Fluent/ColorPicker.xaml
+++ b/src/Avalonia.Controls.ColorPicker/Themes/Fluent/ColorPicker.xaml
@@ -165,7 +165,7 @@
                     </TabItem.Header>
                     <ListBox Theme="{StaticResource ColorViewPaletteListBoxTheme}"
                              ItemContainerTheme="{StaticResource ColorViewPaletteListBoxItemTheme}"
-                             Items="{TemplateBinding PaletteColors}"
+                             ItemsSource="{TemplateBinding PaletteColors}"
                              SelectedItem="{Binding Color, RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource DoNothingForNullConverter}, Mode=TwoWay}"
                              UseLayoutRounding="False"
                              Margin="12">
diff --git a/src/Avalonia.Controls.ColorPicker/Themes/Fluent/ColorView.xaml b/src/Avalonia.Controls.ColorPicker/Themes/Fluent/ColorView.xaml
index fab5415bfb..bcf1f96d22 100644
--- a/src/Avalonia.Controls.ColorPicker/Themes/Fluent/ColorView.xaml
+++ b/src/Avalonia.Controls.ColorPicker/Themes/Fluent/ColorView.xaml
@@ -414,7 +414,7 @@
               </TabItem.Header>
               <ListBox Theme="{StaticResource ColorViewPaletteListBoxTheme}"
                        ItemContainerTheme="{StaticResource ColorViewPaletteListBoxItemTheme}"
-                       Items="{TemplateBinding PaletteColors}"
+                       ItemsSource="{TemplateBinding PaletteColors}"
                        SelectedItem="{Binding Color, RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource DoNothingForNullConverter}, Mode=TwoWay}"
                        UseLayoutRounding="False"
                        Margin="12">
diff --git a/src/Avalonia.Controls.ColorPicker/Themes/Simple/ColorPicker.xaml b/src/Avalonia.Controls.ColorPicker/Themes/Simple/ColorPicker.xaml
index d44902dd70..458f67ec4c 100644
--- a/src/Avalonia.Controls.ColorPicker/Themes/Simple/ColorPicker.xaml
+++ b/src/Avalonia.Controls.ColorPicker/Themes/Simple/ColorPicker.xaml
@@ -165,7 +165,7 @@
                     </TabItem.Header>
                     <ListBox Theme="{StaticResource ColorViewPaletteListBoxTheme}"
                              ItemContainerTheme="{StaticResource ColorViewPaletteListBoxItemTheme}"
-                             Items="{TemplateBinding PaletteColors}"
+                             ItemsSource="{TemplateBinding PaletteColors}"
                              SelectedItem="{Binding Color, RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource DoNothingForNullConverter}, Mode=TwoWay}"
                              UseLayoutRounding="False"
                              Margin="12">
diff --git a/src/Avalonia.Controls.ColorPicker/Themes/Simple/ColorView.xaml b/src/Avalonia.Controls.ColorPicker/Themes/Simple/ColorView.xaml
index 0ce6dd5e04..a4fb7081ca 100644
--- a/src/Avalonia.Controls.ColorPicker/Themes/Simple/ColorView.xaml
+++ b/src/Avalonia.Controls.ColorPicker/Themes/Simple/ColorView.xaml
@@ -376,7 +376,7 @@
               </TabItem.Header>
               <ListBox Theme="{StaticResource ColorViewPaletteListBoxTheme}"
                        ItemContainerTheme="{StaticResource ColorViewPaletteListBoxItemTheme}"
-                       Items="{TemplateBinding PaletteColors}"
+                       ItemsSource="{TemplateBinding PaletteColors}"
                        SelectedItem="{Binding Color, RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource DoNothingForNullConverter}, Mode=TwoWay}"
                        UseLayoutRounding="False"
                        Margin="12">
diff --git a/src/Avalonia.Controls.DataGrid/DataGridCheckBoxColumn.cs b/src/Avalonia.Controls.DataGrid/DataGridCheckBoxColumn.cs
index 39c1e4c118..5d080f5ef6 100644
--- a/src/Avalonia.Controls.DataGrid/DataGridCheckBoxColumn.cs
+++ b/src/Avalonia.Controls.DataGrid/DataGridCheckBoxColumn.cs
@@ -177,14 +177,14 @@ namespace Avalonia.Controls
                 }
 
                 bool? uneditedValue = editingCheckBox.IsChecked;
-                if(editingEventArgs is PointerPressedEventArgs args)
+                if (editingEventArgs is PointerPressedEventArgs args)
                 {
                     void ProcessPointerArgs()
                     {
                         // Editing was triggered by a mouse click
                         Point position = args.GetPosition(editingCheckBox);
                         Rect rect = new Rect(0, 0, editingCheckBox.Bounds.Width, editingCheckBox.Bounds.Height);
-                        if(rect.Contains(position))
+                        if (rect.Contains(position))
                         {
                             EditValue();
                         }
@@ -192,14 +192,14 @@ namespace Avalonia.Controls
                     
                     void OnLayoutUpdated(object sender, EventArgs e)
                     {
-                        if(!editingCheckBox.Bounds.IsDefault)
+                        if (editingCheckBox.Bounds.Width != 0 || editingCheckBox.Bounds.Height != 0)
                         {
                             editingCheckBox.LayoutUpdated -= OnLayoutUpdated;
                             ProcessPointerArgs();
                         }
                     }
 
-                    if(editingCheckBox.Bounds.IsDefault)
+                    if (editingCheckBox.Bounds.Width == 0 && editingCheckBox.Bounds.Height == 0)
                     {
                         editingCheckBox.LayoutUpdated += OnLayoutUpdated;
                     }
diff --git a/src/Avalonia.Controls.ItemsRepeater/Controls/ItemsRepeater.cs b/src/Avalonia.Controls.ItemsRepeater/Controls/ItemsRepeater.cs
index 3d3d01e06e..499904deac 100644
--- a/src/Avalonia.Controls.ItemsRepeater/Controls/ItemsRepeater.cs
+++ b/src/Avalonia.Controls.ItemsRepeater/Controls/ItemsRepeater.cs
@@ -39,7 +39,10 @@ namespace Avalonia.Controls
         /// Defines the <see cref="Items"/> property.
         /// </summary>
         public static readonly DirectProperty<ItemsRepeater, IEnumerable?> ItemsProperty =
-            ItemsControl.ItemsProperty.AddOwner<ItemsRepeater>(o => o.Items, (o, v) => o.Items = v);
+            AvaloniaProperty.RegisterDirect<ItemsRepeater, IEnumerable?>(
+                nameof(Items),
+                o => o.Items,
+                (o, v) => o.Items = v);
 
         /// <summary>
         /// Defines the <see cref="Layout"/> property.
diff --git a/src/Avalonia.Controls.ItemsRepeater/Controls/ViewportManager.cs b/src/Avalonia.Controls.ItemsRepeater/Controls/ViewportManager.cs
index 6ed817c238..6e9cf2f0cf 100644
--- a/src/Avalonia.Controls.ItemsRepeater/Controls/ViewportManager.cs
+++ b/src/Avalonia.Controls.ItemsRepeater/Controls/ViewportManager.cs
@@ -441,7 +441,7 @@ namespace Avalonia.Controls
 
             _pendingViewportShift = default;
             _unshiftableShift = default;
-            if (_visibleWindow.IsDefault)
+            if (_visibleWindow.Width == 0 && _visibleWindow.Height == 0)
             {
                 // We got cleared.
                 _layoutExtent = default;
@@ -527,7 +527,7 @@ namespace Avalonia.Controls
         private void TryInvalidateMeasure()
         {
             // Don't invalidate measure if we have an invalid window.
-            if (!_visibleWindow.IsDefault)
+            if (_visibleWindow.Width != 0 || _visibleWindow.Height != 0)
             {
                 // We invalidate measure instead of just invalidating arrange because
                 // we don't invalidate measure in UpdateViewport if the view is changing to
diff --git a/src/Avalonia.Controls/AutoCompleteBox/AutoCompleteBox.Properties.cs b/src/Avalonia.Controls/AutoCompleteBox/AutoCompleteBox.Properties.cs
index ecbe01d8b7..93b057e176 100644
--- a/src/Avalonia.Controls/AutoCompleteBox/AutoCompleteBox.Properties.cs
+++ b/src/Avalonia.Controls/AutoCompleteBox/AutoCompleteBox.Properties.cs
@@ -87,12 +87,10 @@ namespace Avalonia.Controls
         /// Identifies the <see cref="Text" /> property.
         /// </summary>
         /// <value>The identifier for the <see cref="Text" /> property.</value>
-        public static readonly DirectProperty<AutoCompleteBox, string?> TextProperty =
-            TextBlock.TextProperty.AddOwnerWithDataValidation<AutoCompleteBox>(
-                o => o.Text,
-                (o, v) => o.Text = v,
+        public static readonly StyledProperty<string?> TextProperty =
+            TextBlock.TextProperty.AddOwner<AutoCompleteBox>(new(string.Empty,
                 defaultBindingMode: BindingMode.TwoWay,
-                enableDataValidation: true);
+                enableDataValidation: true));
 
         /// <summary>
         /// Identifies the <see cref="SearchText" /> property.
@@ -317,8 +315,8 @@ namespace Avalonia.Controls
         /// <see cref="AutoCompleteBox" /> control.</value>
         public string? Text
         {
-            get => _text;
-            set => SetAndRaise(TextProperty, ref _text, value);
+            get => GetValue(TextProperty);
+            set => SetValue(TextProperty, value);
         }
 
         /// <summary>
diff --git a/src/Avalonia.Controls/AutoCompleteBox/AutoCompleteBox.cs b/src/Avalonia.Controls/AutoCompleteBox/AutoCompleteBox.cs
index 9a949e31d4..2d074ef7fa 100644
--- a/src/Avalonia.Controls/AutoCompleteBox/AutoCompleteBox.cs
+++ b/src/Avalonia.Controls/AutoCompleteBox/AutoCompleteBox.cs
@@ -198,7 +198,6 @@ namespace Avalonia.Controls
         private bool _isDropDownOpen;
         private bool _isFocused = false;
 
-        private string? _text = string.Empty;
         private string? _searchText = string.Empty;
 
         private AutoCompleteFilterPredicate<object?>? _itemFilter;
@@ -1275,7 +1274,7 @@ namespace Avalonia.Controls
             if ((userInitiated ?? true) && Text != value)
             {
                 _ignoreTextPropertyChange++;
-                Text = value;
+                SetCurrentValue(TextProperty, value);
                 callTextChanged = true;
             }
 
diff --git a/src/Avalonia.Controls/BorderVisual.cs b/src/Avalonia.Controls/BorderVisual.cs
index b0e5c30e2f..591604a3c5 100644
--- a/src/Avalonia.Controls/BorderVisual.cs
+++ b/src/Avalonia.Controls/BorderVisual.cs
@@ -50,7 +50,7 @@ class CompositionBorderVisual : CompositionDrawListVisual
             if (ClipToBounds)
             {
                 var clipRect = Root!.SnapToDevicePixels(new Rect(new Size(Size.X, Size.Y)));
-                if (_cornerRadius.IsDefault)
+                if (_cornerRadius == default)
                     canvas.PushClip(clipRect);
                 else
                     canvas.PushClip(new RoundedRect(clipRect, _cornerRadius));
diff --git a/src/Avalonia.Controls/ContainerClearingEventArgs.cs b/src/Avalonia.Controls/ContainerClearingEventArgs.cs
new file mode 100644
index 0000000000..fb0c5c4bf8
--- /dev/null
+++ b/src/Avalonia.Controls/ContainerClearingEventArgs.cs
@@ -0,0 +1,20 @@
+using System;
+
+namespace Avalonia.Controls
+{
+    /// <summary>
+    /// Provides data for the <see cref="ItemsControl.ContainerClearing"/> event.
+    /// </summary>
+    public class ContainerClearingEventArgs : EventArgs
+    {
+        public ContainerClearingEventArgs(Control container)
+        {
+            Container = container;
+        }
+
+        /// <summary>
+        /// Gets the prepared container.
+        /// </summary>
+        public Control Container { get; }
+    }
+}
diff --git a/src/Avalonia.Controls/ContainerIndexChangedEventArgs.cs b/src/Avalonia.Controls/ContainerIndexChangedEventArgs.cs
new file mode 100644
index 0000000000..80536e742c
--- /dev/null
+++ b/src/Avalonia.Controls/ContainerIndexChangedEventArgs.cs
@@ -0,0 +1,32 @@
+using System;
+
+namespace Avalonia.Controls
+{
+    /// <summary>
+    /// Provides data for the <see cref="ItemsControl.ContainerIndexChanged"/> event.
+    /// </summary>
+    public class ContainerIndexChangedEventArgs : EventArgs
+    {
+        public ContainerIndexChangedEventArgs(Control container, int oldIndex, int newIndex)
+        {
+            Container = container;
+            OldIndex = oldIndex;
+            NewIndex = newIndex;
+        }
+
+        /// <summary>
+        /// Get the container for which the index changed.
+        /// </summary>
+        public Control Container { get; }
+
+        /// <summary>
+        /// Gets the index of the container after the change.
+        /// </summary>
+        public int NewIndex { get; }
+
+        /// <summary>
+        /// Gets the index of the container before the change.
+        /// </summary>
+        public int OldIndex { get; }
+    }
+}
diff --git a/src/Avalonia.Controls/ContainerPreparedEventArgs.cs b/src/Avalonia.Controls/ContainerPreparedEventArgs.cs
new file mode 100644
index 0000000000..1acb653bd1
--- /dev/null
+++ b/src/Avalonia.Controls/ContainerPreparedEventArgs.cs
@@ -0,0 +1,26 @@
+using System;
+
+namespace Avalonia.Controls
+{
+    /// <summary>
+    /// Provides data for the <see cref="ItemsControl.ContainerPrepared"/> event.
+    /// </summary>
+    public class ContainerPreparedEventArgs : EventArgs
+    {
+        public ContainerPreparedEventArgs(Control container, int index)
+        {
+            Container = container;
+            Index = index;
+        }
+
+        /// <summary>
+        /// Gets the prepared container.
+        /// </summary>
+        public Control Container { get; }
+
+        /// <summary>
+        /// Gets the index of the item the container was prepared for.
+        /// </summary>
+        public int Index { get; }
+    }
+}
diff --git a/src/Avalonia.Controls/ContextMenu.cs b/src/Avalonia.Controls/ContextMenu.cs
index 0e7d31967c..f46594ff96 100644
--- a/src/Avalonia.Controls/ContextMenu.cs
+++ b/src/Avalonia.Controls/ContextMenu.cs
@@ -54,11 +54,17 @@ namespace Avalonia.Controls
         public static readonly StyledProperty<PopupGravity> PlacementGravityProperty =
             Popup.PlacementGravityProperty.AddOwner<ContextMenu>();
 
+        /// <summary>
+        /// Defines the <see cref="Placement"/> property.
+        /// </summary>
+        public static readonly StyledProperty<PlacementMode> PlacementProperty =
+            Popup.PlacementProperty.AddOwner<ContextMenu>();
+
         /// <summary>
         /// Defines the <see cref="PlacementMode"/> property.
         /// </summary>
-        public static readonly StyledProperty<PlacementMode> PlacementModeProperty =
-            Popup.PlacementModeProperty.AddOwner<ContextMenu>();
+        [Obsolete("Use the Placement property instead.")]
+        public static readonly StyledProperty<PlacementMode> PlacementModeProperty = PlacementProperty;
 
         /// <summary>
         /// Defines the <see cref="PlacementRect"/> property.
@@ -108,99 +114,80 @@ namespace Avalonia.Controls
         static ContextMenu()
         {
             ItemsPanelProperty.OverrideDefaultValue<ContextMenu>(DefaultPanel);
-            PlacementModeProperty.OverrideDefaultValue<ContextMenu>(PlacementMode.Pointer);
+            PlacementProperty.OverrideDefaultValue<ContextMenu>(PlacementMode.Pointer);
             ContextMenuProperty.Changed.Subscribe(ContextMenuChanged);
             AutomationProperties.AccessibilityViewProperty.OverrideDefaultValue<ContextMenu>(AccessibilityView.Control);
             AutomationProperties.ControlTypeOverrideProperty.OverrideDefaultValue<ContextMenu>(AutomationControlType.Menu);
         }
 
-        /// <summary>
-        /// Gets or sets the Horizontal offset of the context menu in relation to the <see cref="PlacementTarget"/>.
-        /// </summary>
+        /// <inheritdoc cref="Popup.HorizontalOffset"/>
         public double HorizontalOffset
         {
-            get { return GetValue(HorizontalOffsetProperty); }
-            set { SetValue(HorizontalOffsetProperty, value); }
+            get => GetValue(HorizontalOffsetProperty);
+            set => SetValue(HorizontalOffsetProperty, value);
         }
 
-        /// <summary>
-        /// Gets or sets the Vertical offset of the context menu in relation to the <see cref="PlacementTarget"/>.
-        /// </summary>
+        /// <inheritdoc cref="Popup.VerticalOffset"/>
         public double VerticalOffset
         {
-            get { return GetValue(VerticalOffsetProperty); }
-            set { SetValue(VerticalOffsetProperty, value); }
+            get => GetValue(VerticalOffsetProperty);
+            set => SetValue(VerticalOffsetProperty, value);
         }
 
-        /// <summary>
-        /// Gets or sets the anchor point on the <see cref="PlacementRect"/> when <see cref="PlacementMode"/>
-        /// is <see cref="PlacementMode.AnchorAndGravity"/>.
-        /// </summary>
+        /// <inheritdoc cref="Popup.PlacementAnchor"/>
         public PopupAnchor PlacementAnchor
         {
-            get { return GetValue(PlacementAnchorProperty); }
-            set { SetValue(PlacementAnchorProperty, value); }
+            get => GetValue(PlacementAnchorProperty);
+            set => SetValue(PlacementAnchorProperty, value);
         }
 
-        /// <summary>
-        /// Gets or sets a value describing how the context menu position will be adjusted if the
-        /// unadjusted position would result in the context menu being partly constrained.
-        /// </summary>
+        /// <inheritdoc cref="Popup.PlacementConstraintAdjustment"/>
         public PopupPositionerConstraintAdjustment PlacementConstraintAdjustment
         {
-            get { return GetValue(PlacementConstraintAdjustmentProperty); }
-            set { SetValue(PlacementConstraintAdjustmentProperty, value); }
+            get => GetValue(PlacementConstraintAdjustmentProperty);
+            set => SetValue(PlacementConstraintAdjustmentProperty, value);
         }
 
-        /// <summary>
-        /// Gets or sets a value which defines in what direction the context menu should open
-        /// when <see cref="PlacementMode"/> is <see cref="PlacementMode.AnchorAndGravity"/>.
-        /// </summary>
+        /// <inheritdoc cref="Popup.PlacementGravity"/>
         public PopupGravity PlacementGravity
         {
-            get { return GetValue(PlacementGravityProperty); }
-            set { SetValue(PlacementGravityProperty, value); }
+            get => GetValue(PlacementGravityProperty);
+            set => SetValue(PlacementGravityProperty, value);
         }
 
-        /// <summary>
-        /// Gets or sets the placement mode of the context menu in relation to the<see cref="PlacementTarget"/>.
-        /// </summary>
+        /// <inheritdoc cref="Placement"/>
+        [Obsolete("Use the Placement property instead.")]
         public PlacementMode PlacementMode
         {
-            get { return GetValue(PlacementModeProperty); }
-            set { SetValue(PlacementModeProperty, value); }
+            get => GetValue(PlacementProperty);
+            set => SetValue(PlacementProperty, value);
+        }
+
+        /// <inheritdoc cref="Popup.Placement"/>
+        public PlacementMode Placement
+        {
+            get => GetValue(PlacementProperty);
+            set => SetValue(PlacementProperty, value);
         }
 
         public bool WindowManagerAddShadowHint
         {
-            get { return GetValue(WindowManagerAddShadowHintProperty); }
-            set { SetValue(WindowManagerAddShadowHintProperty, value); }
+            get => GetValue(WindowManagerAddShadowHintProperty);
+            set => SetValue(WindowManagerAddShadowHintProperty, value);
         }
 
-        /// <summary>
-        /// Gets or sets the the anchor rectangle within the parent that the context menu will be placed
-        /// relative to when <see cref="PlacementMode"/> is <see cref="PlacementMode.AnchorAndGravity"/>.
-        /// </summary>
-        /// <remarks>
-        /// The placement rect defines a rectangle relative to <see cref="PlacementTarget"/> around
-        /// which the popup will be opened, with <see cref="PlacementAnchor"/> determining which edge
-        /// of the placement target is used.
-        /// 
-        /// If unset, the anchor rectangle will be the bounds of the <see cref="PlacementTarget"/>.
-        /// </remarks>
+        /// <inheritdoc cref="Popup.PlacementRect"/>
         public Rect? PlacementRect
         {
-            get { return GetValue(PlacementRectProperty); }
-            set { SetValue(PlacementRectProperty, value); }
+            get => GetValue(PlacementRectProperty);
+            set => SetValue(PlacementRectProperty, value);
         }
 
-        /// <summary>
-        /// Gets or sets the control that is used to determine the popup's position.
-        /// </summary>
+        /// <inheritdoc cref="Popup.PlacementTarget"/>
         public Control? PlacementTarget
         {
-            get { return GetValue(PlacementTargetProperty); }
-            set { SetValue(PlacementTargetProperty, value); }
+            get => GetValue(PlacementTargetProperty);
+            set => SetValue(PlacementTargetProperty, value);
         }
 
         /// <summary>
@@ -343,9 +330,9 @@ namespace Avalonia.Controls
                 ((ISetLogicalParent)_popup).SetParent(control);
             }
 
-            _popup.PlacementMode = !requestedByPointer && PlacementMode == PlacementMode.Pointer
+            _popup.Placement = !requestedByPointer && Placement == PlacementMode.Pointer
                 ? PlacementMode.Bottom
-                : PlacementMode;
+                : Placement;
 
             //Position of the line below is really important. 
             //All styles are being applied only when control has logical parent.
diff --git a/src/Avalonia.Controls/DateTimePickers/DatePicker.cs b/src/Avalonia.Controls/DateTimePickers/DatePicker.cs
index 118183102a..f3faef26dd 100644
--- a/src/Avalonia.Controls/DateTimePickers/DatePicker.cs
+++ b/src/Avalonia.Controls/DateTimePickers/DatePicker.cs
@@ -389,7 +389,7 @@ namespace Avalonia.Controls
 
             _presenter.Date = SelectedDate ?? DateTimeOffset.Now;
 
-            _popup.PlacementMode = PlacementMode.AnchorAndGravity;
+            _popup.Placement = PlacementMode.AnchorAndGravity;
             _popup.PlacementAnchor = Primitives.PopupPositioning.PopupAnchor.Bottom;
             _popup.PlacementGravity = Primitives.PopupPositioning.PopupGravity.Bottom;
             _popup.PlacementConstraintAdjustment = Primitives.PopupPositioning.PopupPositionerConstraintAdjustment.SlideY;
diff --git a/src/Avalonia.Controls/DateTimePickers/TimePicker.cs b/src/Avalonia.Controls/DateTimePickers/TimePicker.cs
index 2f49a44b8c..0046e1de52 100644
--- a/src/Avalonia.Controls/DateTimePickers/TimePicker.cs
+++ b/src/Avalonia.Controls/DateTimePickers/TimePicker.cs
@@ -255,7 +255,7 @@ namespace Avalonia.Controls
 
             _presenter.Time = SelectedTime ?? DateTime.Now.TimeOfDay;
 
-            _popup.PlacementMode = PlacementMode.AnchorAndGravity;
+            _popup.Placement = PlacementMode.AnchorAndGravity;
             _popup.PlacementAnchor = Primitives.PopupPositioning.PopupAnchor.Bottom;
             _popup.PlacementGravity = Primitives.PopupPositioning.PopupGravity.Bottom;
             _popup.PlacementConstraintAdjustment = Primitives.PopupPositioning.PopupPositionerConstraintAdjustment.SlideY;
diff --git a/src/Avalonia.Controls/Documents/InlineCollection.cs b/src/Avalonia.Controls/Documents/InlineCollection.cs
index fe9f5e64a8..39750d3672 100644
--- a/src/Avalonia.Controls/Documents/InlineCollection.cs
+++ b/src/Avalonia.Controls/Documents/InlineCollection.cs
@@ -91,11 +91,11 @@ namespace Avalonia.Controls.Documents
 
         public override void Add(Inline inline)
         {
-            if (InlineHost is TextBlock textBlock && !string.IsNullOrEmpty(textBlock._text))
+            if (InlineHost is TextBlock textBlock && !string.IsNullOrEmpty(textBlock.Text))
             {
-                base.Add(new Run(textBlock._text));
+                base.Add(new Run(textBlock.Text));
 
-                textBlock._text = null;
+                textBlock.ClearTextInternal();
             }
 
             base.Add(inline);
@@ -113,7 +113,7 @@ namespace Avalonia.Controls.Documents
         {
             if (InlineHost is TextBlock textBlock && !textBlock.HasComplexContent)
             {
-                textBlock._text += text;
+                textBlock.Text += text;
             }
             else
             {
diff --git a/src/Avalonia.Controls/Flyouts/MenuFlyout.cs b/src/Avalonia.Controls/Flyouts/MenuFlyout.cs
index df973debc7..ba5489ac25 100644
--- a/src/Avalonia.Controls/Flyouts/MenuFlyout.cs
+++ b/src/Avalonia.Controls/Flyouts/MenuFlyout.cs
@@ -19,7 +19,9 @@ namespace Avalonia.Controls
         /// Defines the <see cref="Items"/> property
         /// </summary>
         public static readonly DirectProperty<MenuFlyout, IEnumerable?> ItemsProperty =
-            ItemsControl.ItemsProperty.AddOwner<MenuFlyout>(x => x.Items,
+            AvaloniaProperty.RegisterDirect<MenuFlyout, IEnumerable?>(
+                nameof(Items),
+                x => x.Items,
                 (x, v) => x.Items = v);
 
         /// <summary>
diff --git a/src/Avalonia.Controls/Flyouts/PopupFlyoutBase.cs b/src/Avalonia.Controls/Flyouts/PopupFlyoutBase.cs
index a3d05a34b7..9ed4737c7c 100644
--- a/src/Avalonia.Controls/Flyouts/PopupFlyoutBase.cs
+++ b/src/Avalonia.Controls/Flyouts/PopupFlyoutBase.cs
@@ -14,9 +14,9 @@ namespace Avalonia.Controls.Primitives
 {
     public abstract class PopupFlyoutBase : FlyoutBase, IPopupHostProvider
     {
-        /// <inheritdoc cref="Popup.PlacementModeProperty"/>
+        /// <inheritdoc cref="Popup.PlacementProperty"/>
         public static readonly StyledProperty<PlacementMode> PlacementProperty =
-            Popup.PlacementModeProperty.AddOwner<PopupFlyoutBase>();
+            Popup.PlacementProperty.AddOwner<PopupFlyoutBase>();
 
         /// <inheritdoc cref="Popup.HorizontalOffsetProperty"/>
         public static readonly StyledProperty<double> HorizontalOffsetProperty =
@@ -64,15 +64,13 @@ namespace Avalonia.Controls.Primitives
 
         protected Popup Popup => _popupLazy.Value;
 
-        /// <summary>
-        /// Gets or sets the desired placement.
-        /// </summary>
+        /// <inheritdoc cref="Popup.Placement"/>
         public PlacementMode Placement
         {
             get => GetValue(PlacementProperty);
             set => SetValue(PlacementProperty, value);
         }
-        
+
         /// <inheritdoc cref="Popup.PlacementGravity"/>
         public PopupGravity PlacementGravity
         {
@@ -407,7 +405,7 @@ namespace Avalonia.Controls.Primitives
         {
             Size sz;
             // Popup.Child can't be null here, it was set in ShowAtCore.
-            if (Popup.Child!.DesiredSize.IsDefault)
+            if (Popup.Child!.DesiredSize == default)
             {
                 // Popup may not have been shown yet. Measure content
                 sz = LayoutHelper.MeasureChild(Popup.Child, Size.Infinity, new Thickness());
@@ -423,11 +421,11 @@ namespace Avalonia.Controls.Primitives
             Popup.PlacementGravity = PlacementGravity;
             if (showAtPointer)
             {
-                Popup.PlacementMode = PlacementMode.Pointer;
+                Popup.Placement = PlacementMode.Pointer;
             }
             else
             {
-                Popup.PlacementMode = Placement;
+                Popup.Placement = Placement;
                 Popup.PlacementConstraintAdjustment =
                     PopupPositioning.PopupPositionerConstraintAdjustment.SlideX |
                     PopupPositioning.PopupPositionerConstraintAdjustment.SlideY;
diff --git a/src/Avalonia.Controls/ItemCollection.cs b/src/Avalonia.Controls/ItemCollection.cs
new file mode 100644
index 0000000000..c9265558f0
--- /dev/null
+++ b/src/Avalonia.Controls/ItemCollection.cs
@@ -0,0 +1,165 @@
+using System;
+using System.Collections;
+using System.Collections.Specialized;
+using System.Diagnostics.CodeAnalysis;
+using Avalonia.Collections;
+
+namespace Avalonia.Controls
+{
+    /// <summary>
+    /// Holds the list of items that constitute the content of an <see cref="ItemsControl"/>.
+    /// </summary>
+    public class ItemCollection : ItemsSourceView, IList
+    {
+// Suppress "Avoid zero-length array allocations": This is a sentinel value and must be unique.
+#pragma warning disable CA1825
+        private static readonly object?[] s_uninitialized = new object?[0];
+#pragma warning restore CA1825
+
+        private Mode _mode;
+
+        internal ItemCollection()
+            : base(s_uninitialized)
+        {
+        }
+
+        public new object? this[int index]
+        {
+            get => base[index];
+            set => WritableSource[index] = value;
+        }
+
+        public bool IsReadOnly => _mode == Mode.ItemsSource;
+
+        internal event EventHandler? SourceChanged;
+
+        /// <summary>
+        /// Adds an item to the <see cref="ItemsControl"/>.
+        /// </summary>
+        /// <param name="value">The item to add to the collection.</param>
+        /// <returns>
+        /// The position into which the new element was inserted, or -1 to indicate that
+        /// the item was not inserted into the collection.
+        /// </returns>
+        /// <exception cref="InvalidOperationException">
+        /// The collection is in ItemsSource mode.
+        /// </exception>
+        public int Add(object? value) => WritableSource.Add(value);
+
+        /// <summary>
+        /// Clears the collection and releases the references on all items currently in the
+        /// collection.
+        /// </summary>
+        /// <exception cref="InvalidOperationException">
+        /// The collection is in ItemsSource mode.
+        /// </exception>
+        public void Clear() => WritableSource.Clear();
+
+        /// <summary>
+        /// Inserts an element into the collection at the specified index.
+        /// </summary>
+        /// <param name="index">The zero-based index at which to insert the item.</param>
+        /// <param name="value">The item to insert.</param>
+        /// <exception cref="InvalidOperationException">
+        /// The collection is in ItemsSource mode.
+        /// </exception>
+        public void Insert(int index, object? value) => WritableSource.Insert(index, value);
+
+        /// <summary>
+        /// Removes the item at the specified index of the collection or view.
+        /// </summary>
+        /// <param name="index">The zero-based index of the item to remove.</param>
+        /// <exception cref="InvalidOperationException">
+        /// The collection is in ItemsSource mode.
+        /// </exception>
+        public void RemoveAt(int index) => WritableSource.RemoveAt(index);
+
+        /// <summary>
+        /// Removes the specified item reference from the collection or view.
+        /// </summary>
+        /// <param name="value">The object to remove.</param>
+        /// <returns>True if the item was removed; otherwise false.</returns>
+        /// <exception cref="InvalidOperationException">
+        /// The collection is in ItemsSource mode.
+        /// </exception>
+        public bool Remove(object? value)
+        {
+            var c = Count;
+            WritableSource.Remove(value);
+            return Count < c;
+        }
+
+        int IList.Add(object? value) => Add(value);
+        void IList.Clear() => Clear();
+        void IList.Insert(int index, object? value) => Insert(index, value);
+        void IList.RemoveAt(int index) => RemoveAt(index);
+
+        private IList WritableSource
+        {
+            get
+            {
+                if (IsReadOnly)
+                    ThrowIsItemsSource();
+                if (Source == s_uninitialized)
+                    SetSource(CreateDefaultCollection());
+                return Source;
+            }
+        }
+
+        internal IList? GetItemsPropertyValue()
+        {
+            if (_mode == Mode.ObsoleteItemsSetter)
+                return Source == s_uninitialized ? null : Source;
+            return this;
+        }
+
+        internal void SetItems(IList? items)
+        {
+            _mode = Mode.ObsoleteItemsSetter;
+            SetSource(items ?? s_uninitialized);
+        }
+
+        internal void SetItemsSource(IEnumerable? value)
+        {
+            if (_mode != Mode.ItemsSource && Count > 0)
+                throw new InvalidOperationException(
+                    "Items collection must be empty before using ItemsSource.");
+
+            _mode = value is not null ? Mode.ItemsSource : Mode.Items;
+            SetSource(value ?? CreateDefaultCollection());
+        }
+
+        private new void SetSource(IEnumerable source)
+        {
+            var oldSource = Source;
+
+            base.SetSource(source);
+
+            if (oldSource.Count > 0)
+                RaiseCollectionChanged(new(NotifyCollectionChangedAction.Remove, oldSource, 0));
+            if (Source.Count > 0)
+                RaiseCollectionChanged(new(NotifyCollectionChangedAction.Add, Source, 0));
+            SourceChanged?.Invoke(this, EventArgs.Empty);
+        }
+
+        private static AvaloniaList<object?> CreateDefaultCollection()
+        {
+            return new() { ResetBehavior = ResetBehavior.Remove };
+        }
+
+        [DoesNotReturn]
+        private static void ThrowIsItemsSource()
+        {
+            throw new InvalidOperationException(
+                "Operation is not valid while ItemsSource is in use." +
+                "Access and modify elements with ItemsControl.ItemsSource instead.");
+        }
+
+        private enum Mode
+        {
+            Items,
+            ItemsSource,
+            ObsoleteItemsSetter,
+        }
+    }
+}
diff --git a/src/Avalonia.Controls/ItemsControl.cs b/src/Avalonia.Controls/ItemsControl.cs
index bebf4a38f6..4460ff0486 100644
--- a/src/Avalonia.Controls/ItemsControl.cs
+++ b/src/Avalonia.Controls/ItemsControl.cs
@@ -2,6 +2,7 @@ using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Collections.Specialized;
+using System.Diagnostics.CodeAnalysis;
 using Avalonia.Automation.Peers;
 using Avalonia.Collections;
 using Avalonia.Controls.Generators;
@@ -34,8 +35,13 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="Items"/> property.
         /// </summary>
-        public static readonly DirectProperty<ItemsControl, IEnumerable?> ItemsProperty =
-            AvaloniaProperty.RegisterDirect<ItemsControl, IEnumerable?>(nameof(Items), o => o.Items, (o, v) => o.Items = v);
+        public static readonly DirectProperty<ItemsControl, IList?> ItemsProperty =
+            AvaloniaProperty.RegisterDirect<ItemsControl, IList?>(
+                nameof(Items),
+                o => o.Items,
+#pragma warning disable CS0618 // Type or member is obsolete
+                (o, v) => o.Items = v);
+#pragma warning restore CS0618 // Type or member is obsolete
 
         /// <summary>
         /// Defines the <see cref="ItemContainerTheme"/> property.
@@ -56,23 +62,23 @@ namespace Avalonia.Controls
             AvaloniaProperty.Register<ItemsControl, ITemplate<Panel>>(nameof(ItemsPanel), DefaultPanel);
 
         /// <summary>
-        /// Defines the <see cref="ItemTemplate"/> property.
+        /// Defines the <see cref="ItemsSource"/> property.
         /// </summary>
-        public static readonly StyledProperty<IDataTemplate?> ItemTemplateProperty =
-            AvaloniaProperty.Register<ItemsControl, IDataTemplate?>(nameof(ItemTemplate));
+        public static readonly StyledProperty<IEnumerable?> ItemsSourceProperty =
+            AvaloniaProperty.Register<ItemsControl, IEnumerable?>(nameof(ItemsSource));
 
         /// <summary>
-        /// Defines the <see cref="ItemsView"/> property.
+        /// Defines the <see cref="ItemTemplate"/> property.
         /// </summary>
-        public static readonly DirectProperty<ItemsControl, ItemsSourceView> ItemsViewProperty =
-            AvaloniaProperty.RegisterDirect<ItemsControl, ItemsSourceView>(nameof(ItemsView), o => o.ItemsView);
+        public static readonly StyledProperty<IDataTemplate?> ItemTemplateProperty =
+            AvaloniaProperty.Register<ItemsControl, IDataTemplate?>(nameof(ItemTemplate));
 
         /// <summary>
         /// Defines the <see cref="DisplayMemberBinding" /> property
         /// </summary>
         public static readonly StyledProperty<IBinding?> DisplayMemberBindingProperty =
             AvaloniaProperty.Register<ItemsControl, IBinding?>(nameof(DisplayMemberBinding));
-        
+
         /// <summary>
         /// Defines the <see cref="AreHorizontalSnapPointsRegular"/> property.
         /// </summary>
@@ -89,15 +95,15 @@ namespace Avalonia.Controls
         /// Gets or sets the <see cref="IBinding"/> to use for binding to the display member of each item.
         /// </summary>
         [AssignBinding]
+        [InheritDataTypeFromItems(nameof(ItemsSource))]
         [InheritDataTypeFromItems(nameof(Items))]
         public IBinding? DisplayMemberBinding
         {
             get => GetValue(DisplayMemberBindingProperty);
             set => SetValue(DisplayMemberBindingProperty, value);
         }
-        
-        private IEnumerable? _items = new AvaloniaList<object>();
-        private ItemsSourceView _itemsView;
+
+        private readonly ItemCollection _items = new();
         private int _itemCount;
         private ItemContainerGenerator? _itemContainerGenerator;
         private EventHandler<ChildIndexChangedEventArgs>? _childIndexChanged;
@@ -110,9 +116,8 @@ namespace Avalonia.Controls
         /// </summary>
         public ItemsControl()
         {
-            _itemsView = ItemsSourceView.GetOrCreate(_items);
-            _itemsView.PostCollectionChanged += ItemsCollectionChanged;
-            UpdatePseudoClasses(0);
+            UpdatePseudoClasses();
+            _items.CollectionChanged += OnItemsViewCollectionChanged;
         }
 
         /// <summary>
@@ -128,11 +133,45 @@ namespace Avalonia.Controls
         /// <summary>
         /// Gets or sets the items to display.
         /// </summary>
+        /// <remarks>
+        /// Since Avalonia 11, <see cref="ItemsControl"/> has both an <see cref="Items"/> property
+        /// and an <see cref="ItemsSource"/> property. The properties have the following differences:
+        /// 
+        /// <list type="bullet">
+        /// <item><see cref="Items"/> is initialized with an empty collection and is a direct property,
+        /// meaning that it cannot be styled </item>
+        /// <item><see cref="ItemsSource"/> is by default null, and is a styled property. This property
+        /// is marked as the content property and will be used for items added via inline XAML.</item>
+        /// </list>
+        /// 
+        /// In Avalonia 11 the two properties can be used almost interchangeably but this will change
+        /// in a later version. In order to be ready for this change, follow the following guidance:
+        /// 
+        /// <list type="bullet">
+        /// <item>You should use the <see cref="Items"/> property when you're assigning a collection of
+        /// item containers directly, for example adding a collection of <see cref="ListBoxItem"/>s
+        /// directly to a <see cref="ListBox"/>. Add the containers to the pre-existing list, do not
+        /// reassign the <see cref="Items"/> property via the setter or with a binding.</item>
+        /// <item>You should use the <see cref="ItemsSource"/> property when you're assigning or
+        /// binding a collection of models which will be transformed by a data template.</item>
+        /// </list>
+        /// </remarks>
         [Content]
-        public IEnumerable? Items
+        public IList? Items
         {
-            get => _items;
-            set => SetAndRaise(ItemsProperty, ref _items, value);
+            get => _items.GetItemsPropertyValue();
+
+            [Obsolete("Use ItemsSource to set or bind items.")]
+            set
+            {
+                var oldItems = _items.GetItemsPropertyValue();
+
+                if (value != oldItems)
+                {
+                    _items.SetItems(value);
+                    RaisePropertyChanged(ItemsProperty, oldItems, value);
+                }
+            }
         }
 
         /// <summary>
@@ -140,17 +179,24 @@ namespace Avalonia.Controls
         /// </summary>
         public ControlTheme? ItemContainerTheme
         {
-            get => GetValue(ItemContainerThemeProperty); 
+            get => GetValue(ItemContainerThemeProperty);
             set => SetValue(ItemContainerThemeProperty, value);
         }
 
         /// <summary>
-        /// Gets the number of items in <see cref="Items"/>.
+        /// Gets the number of items being displayed by the <see cref="ItemsControl"/>.
         /// </summary>
         public int ItemCount
         {
             get => _itemCount;
-            private set => SetAndRaise(ItemCountProperty, ref _itemCount, value);
+            private set
+            {
+                if (SetAndRaise(ItemCountProperty, ref _itemCount, value))
+                {
+                    UpdatePseudoClasses();
+                    _childIndexChanged?.Invoke(this, ChildIndexChangedEventArgs.TotalCountChanged);
+                }
+            }
         }
 
         /// <summary>
@@ -162,13 +208,46 @@ namespace Avalonia.Controls
             set => SetValue(ItemsPanelProperty, value);
         }
 
+        /// <summary>
+        /// Gets or sets a collection used to generate the content of the <see cref="ItemsControl"/>.
+        /// </summary>
+        /// <remarks>
+        /// Since Avalonia 11, <see cref="ItemsControl"/> has both an <see cref="Items"/> property
+        /// and an <see cref="ItemsSource"/> property. The properties have the following differences:
+        /// 
+        /// <list type="bullet">
+        /// <item><see cref="Items"/> is initialized with an empty collection and is a direct property,
+        /// meaning that it cannot be styled </item>
+        /// <item><see cref="ItemsSource"/> is by default null, and is a styled property. This property
+        /// is marked as the content property and will be used for items added via inline XAML.</item>
+        /// </list>
+        /// 
+        /// In Avalonia 11 the two properties can be used almost interchangeably but this will change
+        /// in a later version. In order to be ready for this change, follow the following guidance:
+        /// 
+        /// <list type="bullet">
+        /// <item>You should use the <see cref="Items"/> property when you're assigning a collection of
+        /// item containers directly, for example adding a collection of <see cref="ListBoxItem"/>s
+        /// directly to a <see cref="ListBox"/>. Add the containers to the pre-existing list, do not
+        /// reassign the <see cref="Items"/> property via the setter or with a binding.</item>
+        /// <item>You should use the <see cref="ItemsSource"/> property when you're assigning or
+        /// binding a collection of models which will be transformed by a data template.</item>
+        /// </list>
+        /// </remarks>
+        public IEnumerable? ItemsSource
+        {
+            get => GetValue(ItemsSourceProperty);
+            set => SetValue(ItemsSourceProperty, value);
+        }
+
         /// <summary>
         /// Gets or sets the data template used to display the items in the control.
         /// </summary>
+        [InheritDataTypeFromItems(nameof(ItemsSource))]
         [InheritDataTypeFromItems(nameof(Items))]
         public IDataTemplate? ItemTemplate
         {
-            get => GetValue(ItemTemplateProperty); 
+            get => GetValue(ItemTemplateProperty);
             set => SetValue(ItemTemplateProperty, value);
         }
 
@@ -183,31 +262,9 @@ namespace Avalonia.Controls
         public Panel? ItemsPanelRoot => Presenter?.Panel;
 
         /// <summary>
-        /// Gets a standardized view over <see cref="Items"/>.
+        /// Gets a read-only view of the items in the <see cref="ItemsControl"/>.
         /// </summary>
-        /// <remarks>
-        /// The <see cref="Items"/> property may be an enumerable which does not implement
-        /// <see cref="IList"/> or may be null. This view can be used to provide a standardized
-        /// view of the current items regardless of the type of the concrete collection, and
-        /// without having to deal with null values.
-        /// </remarks>
-        public ItemsSourceView ItemsView 
-        {
-            get => _itemsView;
-            private set
-            {
-                if (ReferenceEquals(_itemsView, value))
-                    return;
-
-                var oldValue = _itemsView;
-                RemoveControlItemsFromLogicalChildren(_itemsView);
-                _itemsView.PostCollectionChanged -= ItemsCollectionChanged;
-                _itemsView = value;
-                _itemsView.PostCollectionChanged += ItemsCollectionChanged;
-                AddControlItemsToLogicalChildren(_itemsView);
-                RaisePropertyChanged(ItemsViewProperty, oldValue, _itemsView);
-            }
-        }
+        public ItemsSourceView ItemsView => _items;
 
         private protected bool WrapFocus { get; set; }
 
@@ -217,6 +274,34 @@ namespace Avalonia.Controls
             remove => _childIndexChanged -= value;
         }
 
+        /// <summary>
+        /// Occurs each time a container is prepared for use.
+        /// </summary>
+        /// <remarks>
+        /// The prepared element might be newly created or an existing container that is being re-
+        /// used.
+        /// </remarks>
+        public event EventHandler<ContainerPreparedEventArgs>? ContainerPrepared;
+
+        /// <summary>
+        /// Occurs for each realized container when the index for the item it represents has changed.
+        /// </summary>
+        /// <remarks>
+        /// This event is raised for each realized container where the index for the item it
+        /// represents has changed. For example, when another item is added or removed in the data
+        /// source, the index for items that come after in the ordering will be impacted.
+        /// </remarks>
+        public event EventHandler<ContainerIndexChangedEventArgs>? ContainerIndexChanged;
+
+        /// <summary>
+        /// Occurs each time a container is cleared.
+        /// </summary>
+        /// <remarks>
+        /// This event is raised immediately each time an container is cleared, such as when it
+        /// falls outside the range of realized items or the corresponding item is removed.
+        /// </remarks>
+        public event EventHandler<ContainerClearingEventArgs>? ContainerClearing;
+
         /// <inheritdoc />
         public event EventHandler<RoutedEventArgs> HorizontalSnapPointsChanged
         {
@@ -262,7 +347,7 @@ namespace Avalonia.Controls
         /// </summary>
         public bool AreHorizontalSnapPointsRegular
         {
-            get => GetValue(AreHorizontalSnapPointsRegularProperty); 
+            get => GetValue(AreHorizontalSnapPointsRegularProperty);
             set => SetValue(AreHorizontalSnapPointsRegularProperty, value);
         }
 
@@ -271,7 +356,7 @@ namespace Avalonia.Controls
         /// </summary>
         public bool AreVerticalSnapPointsRegular
         {
-            get => GetValue(AreVerticalSnapPointsRegularProperty); 
+            get => GetValue(AreVerticalSnapPointsRegularProperty);
             set => SetValue(AreVerticalSnapPointsRegularProperty, value);
         }
 
@@ -295,7 +380,7 @@ namespace Avalonia.Controls
         /// </returns>
         public Control? ContainerFromItem(object item)
         {
-            var index = ItemsView.IndexOf(item);
+            var index = _items.IndexOf(item);
             return index >= 0 ? ContainerFromIndex(index) : null;
         }
 
@@ -319,7 +404,7 @@ namespace Avalonia.Controls
         public object? ItemFromContainer(Control container)
         {
             var index = IndexFromContainer(container);
-            return index >= 0 && index < ItemsView.Count ? ItemsView[index] : null;
+            return index >= 0 && index < _items.Count ? _items[index] : null;
         }
 
         /// <summary>
@@ -478,19 +563,13 @@ namespace Avalonia.Controls
         {
             base.OnPropertyChanged(change);
 
-            if (change.Property == ItemsProperty)
-            {
-                ItemsView = ItemsSourceView.GetOrCreate(change.GetNewValue<IEnumerable?>());
-                ItemCount = ItemsView.Count;
-            }
-            else if (change.Property == ItemCountProperty)
+            if (change.Property == ItemContainerThemeProperty && _itemContainerGenerator is not null)
             {
-                UpdatePseudoClasses(change.GetNewValue<int>());
-                _childIndexChanged?.Invoke(this, ChildIndexChangedEventArgs.TotalCountChanged);
+                RefreshContainers();
             }
-            else if (change.Property == ItemContainerThemeProperty && _itemContainerGenerator is not null)
+            else if (change.Property == ItemsSourceProperty)
             {
-                RefreshContainers();
+                _items.SetItemsSource(change.GetNewValue<IEnumerable?>());
             }
             else if (change.Property == ItemTemplateProperty)
             {
@@ -517,24 +596,27 @@ namespace Avalonia.Controls
 
         /// <summary>
         /// Called when the <see cref="INotifyCollectionChanged.CollectionChanged"/> event is
-        /// raised on <see cref="Items"/>.
+        /// raised on <see cref="ItemsView"/>.
         /// </summary>
         /// <param name="sender">The event sender.</param>
         /// <param name="e">The event args.</param>
-        protected virtual void ItemsCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
+        private protected virtual void OnItemsViewCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
         {
-            ItemCount = _itemsView.Count;
-
-            switch (e.Action)
+            if (!_items.IsReadOnly)
             {
-                case NotifyCollectionChangedAction.Add:
-                    AddControlItemsToLogicalChildren(e.NewItems);
-                    break;
+                switch (e.Action)
+                {
+                    case NotifyCollectionChangedAction.Add:
+                        AddControlItemsToLogicalChildren(e.NewItems);
+                        break;
 
-                case NotifyCollectionChangedAction.Remove:
-                    RemoveControlItemsFromLogicalChildren(e.OldItems);
-                    break;
+                    case NotifyCollectionChangedAction.Remove:
+                        RemoveControlItemsFromLogicalChildren(e.OldItems);
+                        break;
+                }
             }
+
+            ItemCount = ItemsView.Count;
         }
 
         /// <summary>
@@ -578,7 +660,7 @@ namespace Avalonia.Controls
         {
             var itemContainerTheme = ItemContainerTheme;
 
-            if (itemContainerTheme is not null && 
+            if (itemContainerTheme is not null &&
                 !container.IsSet(ThemeProperty) &&
                 ((IStyleable)container).StyleKey == itemContainerTheme.TargetType)
             {
@@ -595,24 +677,23 @@ namespace Avalonia.Controls
         {
             _childIndexChanged?.Invoke(this, new ChildIndexChangedEventArgs(container, index));
             _scrollViewer?.RegisterAnchorCandidate(container);
+            ContainerPrepared?.Invoke(this, new(container, index));
         }
 
         internal void ItemContainerIndexChanged(Control container, int oldIndex, int newIndex)
         {
             ContainerIndexChangedOverride(container, oldIndex, newIndex);
             _childIndexChanged?.Invoke(this, new ChildIndexChangedEventArgs(container, newIndex));
+            ContainerIndexChanged?.Invoke(this, new(container, oldIndex, newIndex));
         }
 
         internal void ClearItemContainer(Control container)
         {
             _scrollViewer?.UnregisterAnchorCandidate(container);
             ClearContainerForItemOverride(container);
+            ContainerClearing?.Invoke(this, new(container));
         }
 
-        /// <summary>
-        /// Given a collection of items, adds those that are controls to the logical children.
-        /// </summary>
-        /// <param name="items">The items.</param>
         private void AddControlItemsToLogicalChildren(IEnumerable? items)
         {
             if (items is null)
@@ -633,10 +714,6 @@ namespace Avalonia.Controls
                 LogicalChildren.AddRange(toAdd);
         }
 
-        /// <summary>
-        /// Given a collection of items, removes those that are controls to from logical children.
-        /// </summary>
-        /// <param name="items">The items.</param>
         private void RemoveControlItemsFromLogicalChildren(IEnumerable? items)
         {
             if (items is null)
@@ -674,10 +751,10 @@ namespace Avalonia.Controls
             return _displayMemberItemTemplate;
         }
 
-        private void UpdatePseudoClasses(int itemCount)
+        private void UpdatePseudoClasses()
         {
-            PseudoClasses.Set(":empty", itemCount == 0);
-            PseudoClasses.Set(":singleitem", itemCount == 1);
+            PseudoClasses.Set(":empty", ItemCount == 0);
+            PseudoClasses.Set(":singleitem", ItemCount == 1);
         }
 
         protected static IInputElement? GetNextControl(
diff --git a/src/Avalonia.Controls/ItemsSourceView.cs b/src/Avalonia.Controls/ItemsSourceView.cs
index 416b909219..614b70d0ba 100644
--- a/src/Avalonia.Controls/ItemsSourceView.cs
+++ b/src/Avalonia.Controls/ItemsSourceView.cs
@@ -7,6 +7,7 @@ using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Collections.Specialized;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using Avalonia.Controls.Utils;
 
@@ -17,15 +18,16 @@ namespace Avalonia.Controls
     /// and an items control.
     /// </summary>
     public class ItemsSourceView : IReadOnlyList<object?>,
+        IList,
         INotifyCollectionChanged,
         ICollectionChangedListener
     {
         /// <summary>
-        ///  Gets an empty <see cref="ItemsSourceView"/>
+        /// Gets an empty <see cref="ItemsSourceView"/>
         /// </summary>
-        public static ItemsSourceView Empty { get; } = new ItemsSourceView(Array.Empty<object>());
+        public static ItemsSourceView Empty { get; } = new ItemsSourceView(Array.Empty<object?>());
 
-        private readonly IList _inner;
+        private IList _source;
         private NotifyCollectionChangedEventHandler? _collectionChanged;
         private NotifyCollectionChangedEventHandler? _preCollectionChanged;
         private NotifyCollectionChangedEventHandler? _postCollectionChanged;
@@ -35,30 +37,17 @@ namespace Avalonia.Controls
         /// Initializes a new instance of the ItemsSourceView class for the specified data source.
         /// </summary>
         /// <param name="source">The data source.</param>
-        private protected ItemsSourceView(IEnumerable source)
-        {
-            _inner = source switch
-            {
-                ItemsSourceView => throw new ArgumentException("Cannot wrap an existing ItemsSourceView.", nameof(source)),
-                IList list => list,
-                INotifyCollectionChanged => throw new ArgumentException(
-                    "Collection implements INotifyCollectionChanged but not IList.",
-                    nameof(source)),
-                IEnumerable<object> iObj => new List<object>(iObj),
-                null => throw new ArgumentNullException(nameof(source)),
-                _ => new List<object>(source.Cast<object>())
-            };
-        }
+        private protected ItemsSourceView(IEnumerable source) => SetSource(source);
 
         /// <summary>
         /// Gets the number of items in the collection.
         /// </summary>
-        public int Count => Inner.Count;
+        public int Count => Source.Count;
 
         /// <summary>
-        /// Gets the inner collection.
+        /// Gets the source collection.
         /// </summary>
-        public IList Inner => _inner;
+        public IList Source => _source;
 
         /// <summary>
         /// Retrieves the item at the specified index.
@@ -67,12 +56,20 @@ namespace Avalonia.Controls
         /// <returns>The item.</returns>
         public object? this[int index] => GetAt(index);
 
+        bool IList.IsFixedSize => false;
+        bool IList.IsReadOnly => true;
+        bool ICollection.IsSynchronized => false;
+        object ICollection.SyncRoot => this;
+
+        object? IList.this[int index]
+        {
+            get => GetAt(index);
+            set => ThrowReadOnly();
+        }
+
         /// <summary>
-        /// Gets a value that indicates whether the items source can provide a unique key for each item.
-        /// </summary>
-        /// <remarks>
         /// Not implemented in Avalonia, preserved here for ItemsRepeater's usage.
-        /// </remarks>
+        /// </summary>
         internal bool HasKeyIndexMapping => false;
 
         /// <summary>
@@ -131,39 +128,14 @@ namespace Avalonia.Controls
             }
         }
 
-        private void AddListenerIfNecessary()
-        {
-            if (!_listening)
-            {
-                if (_inner is INotifyCollectionChanged incc)
-                    CollectionChangedEventManager.Instance.AddListener(incc, this);
-                _listening = true;
-            }
-        }
-
-        private void RemoveListenerIfNecessary()
-        {
-            if (_listening && _collectionChanged is null && _postCollectionChanged is null)
-            {
-                if (_inner is INotifyCollectionChanged incc)
-                    CollectionChangedEventManager.Instance.RemoveListener(incc, this);
-                _listening = false;
-            }
-        }
-
         /// <summary>
         /// Retrieves the item at the specified index.
         /// </summary>
         /// <param name="index">The index.</param>
         /// <returns>The item.</returns>
-        public object? GetAt(int index) => Inner[index];
-
-        /// <summary>
-        /// Determines the index of a specific item in the collection.
-        /// </summary>
-        /// <param name="item">The object to locate in the collection.</param>
-        /// <returns>The index of value if found in the list; otherwise, -1.</returns>
-        public int IndexOf(object? item) => Inner.IndexOf(item);
+        public object? GetAt(int index) => Source[index];
+        public bool Contains(object? item) => Source.Contains(item);
+        public int IndexOf(object? item) => Source.IndexOf(item);
 
         /// <summary>
         /// Gets or creates an <see cref="ItemsSourceView"/> for the specified enumerable.
@@ -201,7 +173,8 @@ namespace Avalonia.Controls
         {
             return items switch
             {
-                ItemsSourceView<T> isv => isv,
+                ItemsSourceView<T> isvt => isvt,
+                ItemsSourceView isv => new ItemsSourceView<T>(isv.Source),
                 null => ItemsSourceView<T>.Empty,
                 _ => new ItemsSourceView<T>(items)
             };
@@ -236,7 +209,7 @@ namespace Avalonia.Controls
                     yield return o;
             }
 
-            var inner = Inner;
+            var inner = Source;
 
             return inner switch
             {
@@ -245,7 +218,7 @@ namespace Avalonia.Controls
             };
         }
 
-        IEnumerator IEnumerable.GetEnumerator() => Inner.GetEnumerator();
+        IEnumerator IEnumerable.GetEnumerator() => Source.GetEnumerator();
 
         void ICollectionChangedListener.PreChanged(INotifyCollectionChanged sender, NotifyCollectionChangedEventArgs e)
         {
@@ -262,15 +235,69 @@ namespace Avalonia.Controls
             _postCollectionChanged?.Invoke(this, e);
         }
 
+        int IList.Add(object? value) => ThrowReadOnly();
+        void IList.Clear() => ThrowReadOnly();
+        void IList.Insert(int index, object? value) => ThrowReadOnly();
+        void IList.Remove(object? value) => ThrowReadOnly();
+        void IList.RemoveAt(int index) => ThrowReadOnly();
+        void ICollection.CopyTo(Array array, int index) => Source.CopyTo(array, index);
+
         /// <summary>
-        /// Retrieves the index of the item that has the specified unique identifier (key).
+        /// Not implemented in Avalonia, preserved here for ItemsRepeater's usage.
         /// </summary>
-        /// <param name="index">The index.</param>
-        /// <returns>The key</returns>
-        /// <remarks>
-        /// TODO: Not yet implemented in Avalonia.
-        /// </remarks>
         internal string KeyFromIndex(int index) => throw new NotImplementedException();
+
+        private protected void RaiseCollectionChanged(NotifyCollectionChangedEventArgs e)
+        {
+            _preCollectionChanged?.Invoke(this, e);
+            _collectionChanged?.Invoke(this, e);
+            _postCollectionChanged?.Invoke(this, e);
+        }
+
+        [MemberNotNull(nameof(_source))]
+        private protected void SetSource(IEnumerable source)
+        {
+            if (_listening && _source is INotifyCollectionChanged inccOld)
+                CollectionChangedEventManager.Instance.RemoveListener(inccOld, this);
+
+            _source = source switch
+            {
+                ItemsSourceView => throw new ArgumentException("Cannot wrap an existing ItemsSourceView.", nameof(source)),
+                IList list => list,
+                INotifyCollectionChanged => throw new ArgumentException(
+                    "Collection implements INotifyCollectionChanged but not IList.",
+                    nameof(source)),
+                IEnumerable<object> iObj => new List<object>(iObj),
+                null => throw new ArgumentNullException(nameof(source)),
+                _ => new List<object>(source.Cast<object>())
+            };
+
+            if (_listening && _source is INotifyCollectionChanged inccNew)
+                CollectionChangedEventManager.Instance.AddListener(inccNew, this);
+        }
+
+        private void AddListenerIfNecessary()
+        {
+            if (!_listening)
+            {
+                if (_source is INotifyCollectionChanged incc)
+                    CollectionChangedEventManager.Instance.AddListener(incc, this);
+                _listening = true;
+            }
+        }
+
+        private void RemoveListenerIfNecessary()
+        {
+            if (_listening && _collectionChanged is null && _postCollectionChanged is null)
+            {
+                if (_source is INotifyCollectionChanged incc)
+                    CollectionChangedEventManager.Instance.RemoveListener(incc, this);
+                _listening = false;
+            }
+        }
+
+        [DoesNotReturn]
+        private static int ThrowReadOnly() => throw new NotSupportedException("Collection is read-only.");
     }
 
     public sealed class ItemsSourceView<T> : ItemsSourceView, IReadOnlyList<T>
@@ -306,7 +333,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="index">The index.</param>
         /// <returns>The item.</returns>
-        public new T GetAt(int index) => (T)Inner[index]!;
+        public new T GetAt(int index) => (T)Source[index]!;
 
         public new IEnumerator<T> GetEnumerator()
         {
@@ -316,7 +343,7 @@ namespace Avalonia.Controls
                     yield return (T)o;
             }
 
-            var inner = Inner;
+            var inner = Source;
 
             return inner switch
             {
@@ -325,6 +352,6 @@ namespace Avalonia.Controls
             };
         }
 
-        IEnumerator IEnumerable.GetEnumerator() => Inner.GetEnumerator();
+        IEnumerator IEnumerable.GetEnumerator() => Source.GetEnumerator();
     }
 }
diff --git a/src/Avalonia.Controls/LayoutTransformControl.cs b/src/Avalonia.Controls/LayoutTransformControl.cs
index 387dc27562..f747e278f0 100644
--- a/src/Avalonia.Controls/LayoutTransformControl.cs
+++ b/src/Avalonia.Controls/LayoutTransformControl.cs
@@ -91,7 +91,7 @@ namespace Avalonia.Controls
             arrangedsize = TransformRoot.Bounds.Size;
 
             // This is the first opportunity under Silverlight to find out the Child's true DesiredSize
-            if (IsSizeSmaller(finalSizeTransformed, arrangedsize) && _childActualSize.IsDefault)
+            if (IsSizeSmaller(finalSizeTransformed, arrangedsize) && _childActualSize == default)
             {
                 //// Unfortunately, all the work so far is invalid because the wrong DesiredSize was used
                 //// Make a note of the actual DesiredSize
@@ -122,7 +122,7 @@ namespace Avalonia.Controls
             }
 
             Size measureSize;
-            if (_childActualSize.IsDefault)
+            if (_childActualSize == default)
             {
                 // Determine the largest size after the transformation
                 measureSize = ComputeLargestTransformedSize(availableSize);
diff --git a/src/Avalonia.Controls/MaskedTextBox.cs b/src/Avalonia.Controls/MaskedTextBox.cs
index d397a581dc..8fc9477dc7 100644
--- a/src/Avalonia.Controls/MaskedTextBox.cs
+++ b/src/Avalonia.Controls/MaskedTextBox.cs
@@ -15,9 +15,8 @@ namespace Avalonia.Controls
         public static readonly StyledProperty<bool> AsciiOnlyProperty =
              AvaloniaProperty.Register<MaskedTextBox, bool>(nameof(AsciiOnly));
 
-        public static readonly DirectProperty<MaskedTextBox, CultureInfo?> CultureProperty =
-             AvaloniaProperty.RegisterDirect<MaskedTextBox, CultureInfo?>(nameof(Culture), o => o.Culture,
-                (o, v) => o.Culture = v, CultureInfo.CurrentCulture);
+        public static readonly StyledProperty<CultureInfo?> CultureProperty =
+             AvaloniaProperty.Register<MaskedTextBox, CultureInfo?>(nameof(Culture), CultureInfo.CurrentCulture);
 
         public static readonly StyledProperty<bool> HidePromptOnLeaveProperty =
              AvaloniaProperty.Register<MaskedTextBox, bool>(nameof(HidePromptOnLeave));
@@ -32,26 +31,49 @@ namespace Avalonia.Controls
              AvaloniaProperty.Register<MaskedTextBox, string?>(nameof(Mask), string.Empty);
 
         public static readonly StyledProperty<char> PromptCharProperty =
-             AvaloniaProperty.Register<MaskedTextBox, char>(nameof(PromptChar), '_');
+             AvaloniaProperty.Register<MaskedTextBox, char>(nameof(PromptChar), '_', coerce: CoercePromptChar);
 
-        public static readonly DirectProperty<MaskedTextBox, bool> ResetOnPromptProperty =
-             AvaloniaProperty.RegisterDirect<MaskedTextBox, bool>(nameof(ResetOnPrompt), o => o.ResetOnPrompt, (o, v) => o.ResetOnPrompt = v);
+        public static readonly StyledProperty<bool> ResetOnPromptProperty =
+             AvaloniaProperty.Register<MaskedTextBox, bool>(nameof(ResetOnPrompt), true);
 
-        public static readonly DirectProperty<MaskedTextBox, bool> ResetOnSpaceProperty =
-             AvaloniaProperty.RegisterDirect<MaskedTextBox, bool>(nameof(ResetOnSpace), o => o.ResetOnSpace, (o, v) => o.ResetOnSpace = v);
+        public static readonly StyledProperty<bool> ResetOnSpaceProperty =
+             AvaloniaProperty.Register<MaskedTextBox, bool>(nameof(ResetOnSpace), true);
 
-        private CultureInfo? _culture;
+        private bool _ignoreTextChanges;
 
-        private bool _resetOnPrompt = true;
+        static MaskedTextBox()
+        {
+            PasswordCharProperty.OverrideMetadata<MaskedTextBox>(new('\0', coerce: CoercePasswordChar));
+        }
 
-        private bool _ignoreTextChanges;
+        private static char CoercePasswordChar(AvaloniaObject sender, char baseValue)
+        {
+            if (!MaskedTextProvider.IsValidPasswordChar(baseValue))
+            {
+                throw new ArgumentException($"'{baseValue}' is not a valid value for PasswordChar.");
+            }
+            var textbox = (MaskedTextBox)sender;
+            if (textbox.MaskProvider is { } maskProvider && baseValue == maskProvider.PromptChar)
+            {
+                // Prompt and password chars must be different.
+                throw new InvalidOperationException("PasswordChar and PromptChar values cannot be the same.");
+            }
 
-        private bool _resetOnSpace = true;
+            return baseValue;
+        }
 
-        static MaskedTextBox()
+        private static char CoercePromptChar(AvaloniaObject sender, char baseValue)
         {
-            PasswordCharProperty
-                .OverrideDefaultValue<MaskedTextBox>('\0');
+            if (!MaskedTextProvider.IsValidInputChar(baseValue))
+            {
+                throw new ArgumentException($"'{baseValue}' is not a valid value for PromptChar.");
+            }
+            if (baseValue == sender.GetValue(PasswordCharProperty))
+            {
+                throw new InvalidOperationException("PasswordChar and PromptChar values cannot be the same.");
+            }
+
+            return baseValue;
         }
 
         public MaskedTextBox() { }
@@ -59,6 +81,9 @@ namespace Avalonia.Controls
         /// <summary>
         ///  Constructs the MaskedTextBox with the specified MaskedTextProvider object.
         /// </summary>
+        [System.Diagnostics.CodeAnalysis.SuppressMessage("AvaloniaProperty", 
+            "AVP1012:An AvaloniaObject should use SetCurrentValue when assigning its own StyledProperty or AttachedProperty values", 
+            Justification = "These values are being explicitly provided by a constructor parameter.")]
         public MaskedTextBox(MaskedTextProvider maskedTextProvider)
         {
             if (maskedTextProvider == null)
@@ -87,8 +112,8 @@ namespace Avalonia.Controls
         /// </summary>
         public CultureInfo? Culture
         {
-            get => _culture;
-            set => SetAndRaise(CultureProperty, ref _culture, value);
+            get => GetValue(CultureProperty);
+            set => SetValue(CultureProperty, value);
         }
 
         /// <summary>
@@ -131,15 +156,6 @@ namespace Avalonia.Controls
         /// </summary>
         public MaskedTextProvider? MaskProvider { get; private set; }
 
-        /// <summary>
-        /// Gets or sets the character to be displayed in substitute for user input.
-        /// </summary>
-        public new char PasswordChar
-        {
-            get => GetValue(PasswordCharProperty);
-            set => SetValue(PasswordCharProperty, value);
-        }
-
         /// <summary>
         /// Gets or sets the character used to represent the absence of user input in MaskedTextBox.
         /// </summary>
@@ -154,16 +170,8 @@ namespace Avalonia.Controls
         /// </summary>
         public bool ResetOnPrompt
         {
-            get => _resetOnPrompt;
-            set
-            {
-                SetAndRaise(ResetOnPromptProperty, ref _resetOnPrompt, value);
-                if (MaskProvider != null)
-                {
-                    MaskProvider.ResetOnPrompt = value;
-                }
-
-            }
+            get => GetValue(ResetOnPromptProperty);
+            set => SetValue(ResetOnPromptProperty, value);
         }
 
         /// <summary>
@@ -171,16 +179,8 @@ namespace Avalonia.Controls
         /// </summary>
         public bool ResetOnSpace
         {
-            get => _resetOnSpace;
-            set
-            {
-                SetAndRaise(ResetOnSpaceProperty, ref _resetOnSpace, value);
-                if (MaskProvider != null)
-                {
-                    MaskProvider.ResetOnSpace = value;
-                }
-
-            }
+            get => GetValue(ResetOnSpaceProperty);
+            set => SetValue(ResetOnSpaceProperty, value);
         }
 
         Type IStyleable.StyleKey => typeof(TextBox);
@@ -190,7 +190,7 @@ namespace Avalonia.Controls
         {
             if (HidePromptOnLeave == true && MaskProvider != null)
             {
-                Text = MaskProvider.ToDisplayString();
+                SetCurrentValue(TextProperty, MaskProvider.ToDisplayString());
             }
             base.OnGotFocus(e);
         }
@@ -225,11 +225,11 @@ namespace Avalonia.Controls
                     var index = GetNextCharacterPosition(CaretIndex);
                     if (MaskProvider.InsertAt(item, index))
                     {
-                        CaretIndex = ++index;
+                        SetCurrentValue(CaretIndexProperty, ++index);
                     }
                 }
 
-                Text = MaskProvider.ToDisplayString();
+                SetCurrentValue(TextProperty, MaskProvider.ToDisplayString());
                 e.Handled = true;
                 return;
             }
@@ -279,7 +279,7 @@ namespace Avalonia.Controls
         {
             if (HidePromptOnLeave && MaskProvider != null)
             {
-                Text = MaskProvider.ToString(!HidePromptOnLeave, true);
+                SetCurrentValue(TextProperty, MaskProvider.ToString(!HidePromptOnLeave, true));
             }
             base.OnLostFocus(e);
         }
@@ -326,15 +326,6 @@ namespace Avalonia.Controls
             }
             else if (change.Property == PasswordCharProperty)
             {
-                if (!MaskedTextProvider.IsValidPasswordChar(PasswordChar))
-                {
-                    throw new ArgumentException("Specified character value is not allowed for this property.", nameof(PasswordChar));
-                }
-                if (MaskProvider != null && PasswordChar == MaskProvider.PromptChar)
-                {
-                    // Prompt and password chars must be different.
-                    throw new InvalidOperationException("PasswordChar and PromptChar values cannot be the same.");
-                }
                 if (MaskProvider != null && MaskProvider.PasswordChar != PasswordChar)
                 {
                     UpdateMaskProvider();
@@ -342,17 +333,23 @@ namespace Avalonia.Controls
             }
             else if (change.Property == PromptCharProperty)
             {
-                if (!MaskedTextProvider.IsValidInputChar(PromptChar))
+                if (MaskProvider != null && MaskProvider.PromptChar != PromptChar)
                 {
-                    throw new ArgumentException("Specified character value is not allowed for this property.");
+                    UpdateMaskProvider();
                 }
-                if (PromptChar == PasswordChar)
+            }
+            else if (change.Property == ResetOnPromptProperty)
+            {
+                if (MaskProvider != null && change.GetNewValue<bool>() is { } newValue)
                 {
-                    throw new InvalidOperationException("PasswordChar and PromptChar values cannot be the same.");
+                    MaskProvider.ResetOnPrompt = newValue;
                 }
-                if (MaskProvider != null && MaskProvider.PromptChar != PromptChar)
+            }
+            else if (change.Property == ResetOnSpaceProperty)
+            {
+                if (MaskProvider != null && change.GetNewValue<bool>() is { } newValue)
                 {
-                    UpdateMaskProvider();
+                    MaskProvider.ResetOnSpace = newValue;
                 }
             }
             else if (change.Property == AsciiOnlyProperty && MaskProvider != null && MaskProvider.AsciiOnly != AsciiOnly
@@ -390,7 +387,7 @@ namespace Avalonia.Controls
 
                 if (CaretIndex < Text?.Length)
                 {
-                    CaretIndex = GetNextCharacterPosition(CaretIndex);
+                    SetCurrentValue(CaretIndexProperty, GetNextCharacterPosition(CaretIndex));
 
                     if (MaskProvider.InsertAt(e.Text!, CaretIndex))
                     {
@@ -399,7 +396,7 @@ namespace Avalonia.Controls
                     var nextPos = GetNextCharacterPosition(CaretIndex);
                     if (nextPos != 0 && CaretIndex != Text.Length)
                     {
-                        CaretIndex = nextPos;
+                        SetCurrentValue(CaretIndexProperty, nextPos);
                     }
                 }
 
@@ -434,8 +431,8 @@ namespace Avalonia.Controls
         {
             if (provider != null)
             {
-                Text = provider.ToDisplayString();
-                CaretIndex = position;
+                SetCurrentValue(TextProperty, provider.ToDisplayString());
+                SetCurrentValue(CaretIndexProperty, position);
             }
         }
 
diff --git a/src/Avalonia.Controls/NativeControlHost.cs b/src/Avalonia.Controls/NativeControlHost.cs
index a94a1ee983..aa3d6db9e0 100644
--- a/src/Avalonia.Controls/NativeControlHost.cs
+++ b/src/Avalonia.Controls/NativeControlHost.cs
@@ -141,7 +141,7 @@ namespace Avalonia.Controls
 
             if (IsEffectivelyVisible && bounds.HasValue)
             {
-                if (bounds.Value.IsDefault)
+                if (bounds.Value.Width == 0 && bounds.Value.Height == 0)
                     return false;
                 _attachment?.ShowInBounds(bounds.Value);
             }
diff --git a/src/Avalonia.Controls/Presenters/PanelContainerGenerator.cs b/src/Avalonia.Controls/Presenters/PanelContainerGenerator.cs
index a2df8c3e5f..796ee8433a 100644
--- a/src/Avalonia.Controls/Presenters/PanelContainerGenerator.cs
+++ b/src/Avalonia.Controls/Presenters/PanelContainerGenerator.cs
@@ -22,7 +22,6 @@ namespace Avalonia.Controls.Presenters
             Debug.Assert(presenter.Panel is not null or VirtualizingPanel);
             
             _presenter = presenter;
-            _presenter.ItemsControl.PropertyChanged += OnItemsControlPropertyChanged;
             _presenter.ItemsControl.ItemsView.PostCollectionChanged += OnItemsChanged;
 
             OnItemsChanged(null, CollectionUtils.ResetEventArgs);
@@ -32,9 +31,7 @@ namespace Avalonia.Controls.Presenters
         {
             if (_presenter.ItemsControl is { } itemsControl)
             {
-                itemsControl.PropertyChanged -= OnItemsControlPropertyChanged;
                 itemsControl.ItemsView.PostCollectionChanged -= OnItemsChanged;
-
                 ClearItemsControlLogicalChildren();
             }
 
@@ -43,18 +40,6 @@ namespace Avalonia.Controls.Presenters
 
         internal void Refresh() => OnItemsChanged(null, CollectionUtils.ResetEventArgs);
 
-        private void OnItemsControlPropertyChanged(object? sender, AvaloniaPropertyChangedEventArgs e)
-        {
-            if (e.Property == ItemsControl.ItemsProperty)
-            {
-                if (e.OldValue is INotifyCollectionChanged inccOld)
-                    inccOld.CollectionChanged -= OnItemsChanged;
-                OnItemsChanged(null, CollectionUtils.ResetEventArgs);
-                if (e.NewValue is INotifyCollectionChanged inccNew)
-                    inccNew.CollectionChanged += OnItemsChanged;
-            }
-        }
-
         private void OnItemsChanged(object? sender, NotifyCollectionChangedEventArgs e)
         {
             if (_presenter.Panel is null || _presenter.ItemsControl is null)
@@ -84,8 +69,7 @@ namespace Avalonia.Controls.Presenters
                     var c = children[index + i];
                     if (!c.IsSet(ItemIsOwnContainerProperty))
                         itemsControl.RemoveLogicalChild(children[i + index]);
-                    else
-                        generator.ClearItemContainer(c);
+                    generator.ClearItemContainer(c);
                 }
 
                 children.RemoveRange(index, count);
diff --git a/src/Avalonia.Controls/Presenters/TextPresenter.cs b/src/Avalonia.Controls/Presenters/TextPresenter.cs
index 089a2c1168..e4167425cd 100644
--- a/src/Avalonia.Controls/Presenters/TextPresenter.cs
+++ b/src/Avalonia.Controls/Presenters/TextPresenter.cs
@@ -9,17 +9,13 @@ using Avalonia.VisualTree;
 using Avalonia.Layout;
 using Avalonia.Media.Immutable;
 using Avalonia.Controls.Documents;
-using Avalonia.Input.TextInput;
-using Avalonia.Data;
 
 namespace Avalonia.Controls.Presenters
 {
     public class TextPresenter : Control
     {
-        public static readonly DirectProperty<TextPresenter, int> CaretIndexProperty =
-            TextBox.CaretIndexProperty.AddOwner<TextPresenter>(
-                o => o.CaretIndex,
-                (o, v) => o.CaretIndex = v);
+        public static readonly StyledProperty<int> CaretIndexProperty =
+            TextBox.CaretIndexProperty.AddOwner<TextPresenter>(new(coerce: TextBox.CoerceCaretIndex));
 
         public static readonly StyledProperty<bool> RevealPasswordProperty =
             AvaloniaProperty.Register<TextPresenter, bool>(nameof(RevealPassword));
@@ -36,33 +32,23 @@ namespace Avalonia.Controls.Presenters
         public static readonly StyledProperty<IBrush?> CaretBrushProperty =
             AvaloniaProperty.Register<TextPresenter, IBrush?>(nameof(CaretBrush));
 
-        public static readonly DirectProperty<TextPresenter, int> SelectionStartProperty =
-            TextBox.SelectionStartProperty.AddOwner<TextPresenter>(
-                o => o.SelectionStart,
-                (o, v) => o.SelectionStart = v);
+        public static readonly StyledProperty<int> SelectionStartProperty =
+            TextBox.SelectionStartProperty.AddOwner<TextPresenter>(new(coerce: TextBox.CoerceCaretIndex));
 
-        public static readonly DirectProperty<TextPresenter, int> SelectionEndProperty =
-            TextBox.SelectionEndProperty.AddOwner<TextPresenter>(
-                o => o.SelectionEnd,
-                (o, v) => o.SelectionEnd = v);
+        public static readonly StyledProperty<int> SelectionEndProperty =
+            TextBox.SelectionEndProperty.AddOwner<TextPresenter>(new(coerce: TextBox.CoerceCaretIndex));
 
         /// <summary>
         /// Defines the <see cref="Text"/> property.
         /// </summary>
-        public static readonly DirectProperty<TextPresenter, string?> TextProperty =
-            AvaloniaProperty.RegisterDirect<TextPresenter, string?>(
-                nameof(Text),
-                o => o.Text,
-                (o, v) => o.Text = v, defaultBindingMode: BindingMode.OneWay);
+        public static readonly StyledProperty<string?> TextProperty =
+            TextBlock.TextProperty.AddOwner<TextPresenter>(new(string.Empty));
 
         /// <summary>
         /// Defines the <see cref="PreeditText"/> property.
         /// </summary>
-        public static readonly DirectProperty<TextPresenter, string?> PreeditTextProperty =
-            AvaloniaProperty.RegisterDirect<TextPresenter, string?>(
-                nameof(PreeditText),
-                o => o.PreeditText,
-                 (o, v) => o.PreeditText = v);
+        public static readonly StyledProperty<string?> PreeditTextProperty =
+            AvaloniaProperty.Register<TextPresenter, string?>(nameof(PreeditText));
 
         /// <summary>
         /// Defines the <see cref="CompositionRegion"/> property.
@@ -104,18 +90,13 @@ namespace Avalonia.Controls.Presenters
             Border.BackgroundProperty.AddOwner<TextPresenter>();
 
         private readonly DispatcherTimer _caretTimer;
-        private int _caretIndex;
-        private int _selectionStart;
-        private int _selectionEnd;
         private bool _caretBlink;
-        internal string? _text;
         private TextLayout? _textLayout;
         private Size _constraint;
 
         private CharacterHit _lastCharacterHit;
         private Rect _caretBounds;
         private Point _navigationPosition;
-        private string? _preeditText;
         private TextRange? _compositionRegion;
 
         static TextPresenter()
@@ -125,7 +106,6 @@ namespace Avalonia.Controls.Presenters
 
         public TextPresenter()
         {
-            _text = string.Empty;
             _caretTimer = new DispatcherTimer { Interval = TimeSpan.FromMilliseconds(500) };
             _caretTimer.Tick += CaretTimerTick;
         }
@@ -147,14 +127,14 @@ namespace Avalonia.Controls.Presenters
         [Content]
         public string? Text
         {
-            get => _text;
-            set => SetAndRaise(TextProperty, ref _text, value);
+            get => GetValue(TextProperty);
+            set => SetValue(TextProperty, value);
         }
 
         public string? PreeditText
         {
-            get => _preeditText;
-            set => SetAndRaise(PreeditTextProperty, ref _preeditText, value);
+            get => GetValue(PreeditTextProperty);
+            set => SetValue(PreeditTextProperty, value);
         }
 
         public TextRange? CompositionRegion
@@ -275,17 +255,8 @@ namespace Avalonia.Controls.Presenters
 
         public int CaretIndex
         {
-            get
-            {
-                return _caretIndex;
-            }
-            set
-            {
-                if (value != _caretIndex)
-                {
-                    MoveCaretToTextPosition(value);
-                }
-            }
+            get => GetValue(CaretIndexProperty);
+            set => SetValue(CaretIndexProperty, value);
         }
 
         public char PasswordChar
@@ -320,30 +291,14 @@ namespace Avalonia.Controls.Presenters
 
         public int SelectionStart
         {
-            get
-            {
-                return _selectionStart;
-            }
-
-            set
-            {
-                value = CoerceCaretIndex(value);
-                SetAndRaise(SelectionStartProperty, ref _selectionStart, value);
-            }
+            get => GetValue(SelectionStartProperty);
+            set => SetValue(SelectionStartProperty, value);
         }
 
         public int SelectionEnd
         {
-            get
-            {
-                return _selectionEnd;
-            }
-
-            set
-            {
-                value = CoerceCaretIndex(value);
-                SetAndRaise(SelectionEndProperty, ref _selectionEnd, value);
-            }
+            get => GetValue(SelectionEndProperty);
+            set => SetValue(SelectionEndProperty, value);
         }
 
         protected override bool BypassFlowDirectionPolicies => true;
@@ -535,12 +490,12 @@ namespace Avalonia.Controls.Presenters
         {
             TextLayout result;
 
-            var text = _text;
+            var text = Text;
 
             var typeface = new Typeface(FontFamily, FontStyle, FontWeight);
 
-            var selectionStart = CoerceCaretIndex(SelectionStart);
-            var selectionEnd = CoerceCaretIndex(SelectionEnd);
+            var selectionStart = SelectionStart;
+            var selectionEnd = SelectionEnd;
             var start = Math.Min(selectionStart, selectionEnd);
             var length = Math.Max(selectionStart, selectionEnd) - start;
 
@@ -561,9 +516,9 @@ namespace Avalonia.Controls.Presenters
                 };
 
             }
-            else if (!string.IsNullOrEmpty(_preeditText))
+            else if (!string.IsNullOrEmpty(PreeditText))
             {
-                var preeditHighlight = new ValueSpan<TextRunProperties>(_caretIndex, _preeditText.Length,
+                var preeditHighlight = new ValueSpan<TextRunProperties>(CaretIndex, PreeditText.Length,
                         new GenericTextRunProperties(typeface, FontSize,
                         foregroundBrush: foreground,
                         textDecorations: TextDecorations.Underline));
@@ -643,13 +598,6 @@ namespace Avalonia.Controls.Presenters
             return finalSize;
         }
 
-        private int CoerceCaretIndex(int value)
-        {
-            var text = Text;
-            var length = text?.Length ?? 0;
-            return Math.Max(0, Math.Min(length, value));
-        }
-
         private void CaretTimerTick(object? sender, EventArgs e)
         {
             _caretBlink = !_caretBlink;
@@ -865,7 +813,7 @@ namespace Avalonia.Controls.Presenters
 
             if (notify)
             {
-                SetAndRaise(CaretIndexProperty, ref _caretIndex, caretIndex);
+                SetCurrentValue(CaretIndexProperty, caretIndex);
             }
         }
 
@@ -887,6 +835,11 @@ namespace Avalonia.Controls.Presenters
         {
             base.OnPropertyChanged(change);
 
+            if (change.Property == CaretIndexProperty)
+            {
+                MoveCaretToTextPosition(change.GetNewValue<int>());
+            }
+
             switch (change.Property.Name)
             {
                 case nameof(PreeditText):
diff --git a/src/Avalonia.Controls/Primitives/Popup.cs b/src/Avalonia.Controls/Primitives/Popup.cs
index 0c6c434713..eda794f33a 100644
--- a/src/Avalonia.Controls/Primitives/Popup.cs
+++ b/src/Avalonia.Controls/Primitives/Popup.cs
@@ -65,11 +65,17 @@ namespace Avalonia.Controls.Primitives
         public static readonly StyledProperty<PopupGravity> PlacementGravityProperty =
             AvaloniaProperty.Register<Popup, PopupGravity>(nameof(PlacementGravity));
 
+        /// <summary>
+        /// Defines the <see cref="Placement"/> property.
+        /// </summary>
+        public static readonly StyledProperty<PlacementMode> PlacementProperty =
+            AvaloniaProperty.Register<Popup, PlacementMode>(nameof(Placement), defaultValue: PlacementMode.Bottom);
+
         /// <summary>
         /// Defines the <see cref="PlacementMode"/> property.
         /// </summary>
-        public static readonly StyledProperty<PlacementMode> PlacementModeProperty =
-            AvaloniaProperty.Register<Popup, PlacementMode>(nameof(PlacementMode), defaultValue: PlacementMode.Bottom);
+        [Obsolete("Use the Placement property instead.")]
+        public static readonly StyledProperty<PlacementMode> PlacementModeProperty = PlacementProperty;
 
         /// <summary>
         /// Defines the <see cref="PlacementRect"/> property.
@@ -146,8 +152,8 @@ namespace Avalonia.Controls.Primitives
 
         public bool WindowManagerAddShadowHint
         {
-            get { return GetValue(WindowManagerAddShadowHintProperty); }
-            set { SetValue(WindowManagerAddShadowHintProperty, value); }
+            get => GetValue(WindowManagerAddShadowHintProperty);
+            set => SetValue(WindowManagerAddShadowHintProperty, value);
         }
 
         /// <summary>
@@ -156,8 +162,8 @@ namespace Avalonia.Controls.Primitives
         [Content]
         public Control? Child
         {
-            get { return GetValue(ChildProperty); }
-            set { SetValue(ChildProperty, value); }
+            get => GetValue(ChildProperty);
+            set => SetValue(ChildProperty, value);
         }
 
         /// <summary>
@@ -205,13 +211,13 @@ namespace Avalonia.Controls.Primitives
         }
 
         /// <summary>
-        /// Gets or sets the anchor point on the <see cref="PlacementRect"/> when <see cref="PlacementMode"/>
+        /// Gets or sets the anchor point on the <see cref="PlacementRect"/> when <see cref="Placement"/>
         /// is <see cref="PlacementMode.AnchorAndGravity"/>.
         /// </summary>
         public PopupAnchor PlacementAnchor
         {
-            get { return GetValue(PlacementAnchorProperty); }
-            set { SetValue(PlacementAnchorProperty, value); }
+            get => GetValue(PlacementAnchorProperty);
+            set => SetValue(PlacementAnchorProperty, value);
         }
 
         /// <summary>
@@ -220,32 +226,40 @@ namespace Avalonia.Controls.Primitives
         /// </summary>
         public PopupPositionerConstraintAdjustment PlacementConstraintAdjustment
         {
-            get { return GetValue(PlacementConstraintAdjustmentProperty); }
-            set { SetValue(PlacementConstraintAdjustmentProperty, value); }
+            get => GetValue(PlacementConstraintAdjustmentProperty);
+            set => SetValue(PlacementConstraintAdjustmentProperty, value);
         }
 
         /// <summary>
         /// Gets or sets a value which defines in what direction the popup should open
-        /// when <see cref="PlacementMode"/> is <see cref="PlacementMode.AnchorAndGravity"/>.
+        /// when <see cref="Placement"/> is <see cref="PlacementMode.AnchorAndGravity"/>.
         /// </summary>
         public PopupGravity PlacementGravity
         {
-            get { return GetValue(PlacementGravityProperty); }
-            set { SetValue(PlacementGravityProperty, value); }
+            get => GetValue(PlacementGravityProperty);
+            set => SetValue(PlacementGravityProperty, value);
+        }
+
+        /// <inheritdoc cref="Placement"/>
+        [Obsolete("Use the Placement property instead.")]
+        public PlacementMode PlacementMode
+        {
+            get => GetValue(PlacementProperty);
+            set => SetValue(PlacementProperty, value);
         }
 
         /// <summary>
-        /// Gets or sets the placement mode of the popup in relation to the <see cref="PlacementTarget"/>.
+        /// Gets or sets the desired placement of the popup in relation to the <see cref="PlacementTarget"/>.
         /// </summary>
-        public PlacementMode PlacementMode
+        public PlacementMode Placement
         {
-            get { return GetValue(PlacementModeProperty); }
-            set { SetValue(PlacementModeProperty, value); }
+            get => GetValue(PlacementProperty);
+            set => SetValue(PlacementProperty, value);
         }
 
         /// <summary>
         /// Gets or sets the the anchor rectangle within the parent that the popup will be placed
-        /// relative to when <see cref="PlacementMode"/> is <see cref="PlacementMode.AnchorAndGravity"/>.
+        /// relative to when <see cref="Placement"/> is <see cref="PlacementMode.AnchorAndGravity"/>.
         /// </summary>
         /// <remarks>
         /// The placement rect defines a rectangle relative to <see cref="PlacementTarget"/> around
@@ -256,8 +270,8 @@ namespace Avalonia.Controls.Primitives
         /// </remarks>
         public Rect? PlacementRect
         {
-            get { return GetValue(PlacementRectProperty); }
-            set { SetValue(PlacementRectProperty, value); }
+            get => GetValue(PlacementRectProperty);
+            set => SetValue(PlacementRectProperty, value);
         }
 
         /// <summary>
@@ -266,8 +280,8 @@ namespace Avalonia.Controls.Primitives
         [ResolveByName]
         public Control? PlacementTarget
         {
-            get { return GetValue(PlacementTargetProperty); }
-            set { SetValue(PlacementTargetProperty, value); }
+            get => GetValue(PlacementTargetProperty);
+            set => SetValue(PlacementTargetProperty, value);
         }
 
         /// <summary>
@@ -301,8 +315,8 @@ namespace Avalonia.Controls.Primitives
         /// </summary>
         public double HorizontalOffset
         {
-            get { return GetValue(HorizontalOffsetProperty); }
-            set { SetValue(HorizontalOffsetProperty, value); }
+            get => GetValue(HorizontalOffsetProperty);
+            set => SetValue(HorizontalOffsetProperty, value);
         }
 
         /// <summary>
@@ -310,8 +324,8 @@ namespace Avalonia.Controls.Primitives
         /// </summary>
         public double VerticalOffset
         {
-            get { return GetValue(VerticalOffsetProperty); }
-            set { SetValue(VerticalOffsetProperty, value); }
+            get => GetValue(VerticalOffsetProperty);
+            set => SetValue(VerticalOffsetProperty, value);
         }
 
         /// <summary>
@@ -319,8 +333,8 @@ namespace Avalonia.Controls.Primitives
         /// </summary>
         public bool Topmost
         {
-            get { return GetValue(TopmostProperty); }
-            set { SetValue(TopmostProperty, value); }
+            get => GetValue(TopmostProperty);
+            set => SetValue(TopmostProperty, value);
         }
 
         IPopupHost? IPopupHostProvider.PopupHost => Host;
@@ -404,7 +418,7 @@ namespace Avalonia.Controls.Primitives
                     (x, handler) => x.LostFocus -= handler).DisposeWith(handlerCleanup);
 
                 // Recalculate popup position on parent moved/resized, but not if placement was on pointer
-                if (PlacementMode != PlacementMode.Pointer)
+                if (Placement != PlacementMode.Pointer)
                 {
                     SubscribeToEventHandler<IWindowImpl, Action<PixelPoint>>(window.PlatformImpl, WindowPositionChanged,
                         (x, handler) => x.PositionChanged += handler,
@@ -534,7 +548,7 @@ namespace Avalonia.Controls.Primitives
                     UpdateHostSizing(_openState.PopupHost, _openState.TopLevel, _openState.PlacementTarget);
                 }
                 else if (change.Property == PlacementTargetProperty ||
-                         change.Property == PlacementModeProperty ||
+                         change.Property == PlacementProperty ||
                          change.Property == HorizontalOffsetProperty ||
                          change.Property == VerticalOffsetProperty ||
                          change.Property == PlacementAnchorProperty ||
@@ -567,7 +581,7 @@ namespace Avalonia.Controls.Primitives
         {
             popupHost.ConfigurePosition(
                 placementTarget,
-                PlacementMode,
+                Placement,
                 new Point(HorizontalOffset, VerticalOffset),
                 PlacementAnchor,
                 PlacementGravity,
@@ -615,7 +629,7 @@ namespace Avalonia.Controls.Primitives
                     return;
                 _openState.PopupHost.ConfigurePosition(
                     placementTarget,
-                    PlacementMode,
+                    Placement,
                     new Point(HorizontalOffset, VerticalOffset),
                     PlacementAnchor,
                     PlacementGravity,
diff --git a/src/Avalonia.Controls/Primitives/PopupPositioning/ManagedPopupPositioner.cs b/src/Avalonia.Controls/Primitives/PopupPositioning/ManagedPopupPositioner.cs
index 62e5f37273..9a60725c7e 100644
--- a/src/Avalonia.Controls/Primitives/PopupPositioning/ManagedPopupPositioner.cs
+++ b/src/Avalonia.Controls/Primitives/PopupPositioning/ManagedPopupPositioner.cs
@@ -112,7 +112,8 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
                                    ?? screens.FirstOrDefault(s => s.Bounds.Intersects(parentGeometry))
                                    ?? screens.FirstOrDefault();
 
-                if (targetScreen != null && targetScreen.WorkingArea.IsDefault)
+                if (targetScreen != null &&
+                    (targetScreen.WorkingArea.Width == 0 && targetScreen.WorkingArea.Height == 0))
                 {
                     return targetScreen.Bounds;
                 }
diff --git a/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs b/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
index 2ee32b0dda..b89a75787f 100644
--- a/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
+++ b/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
@@ -145,6 +145,11 @@ namespace Avalonia.Controls.Primitives
         private BindingHelper? _bindingHelper;
         private bool _isSelectionChangeActive;
 
+        public SelectingItemsControl()
+        {
+            ((ItemCollection)ItemsView).SourceChanged += OnItemsViewSourceChanged;
+        }
+
         /// <summary>
         /// Initializes static members of the <see cref="SelectingItemsControl"/> class.
         /// </summary>
@@ -229,6 +234,7 @@ namespace Avalonia.Controls.Primitives
         /// <see cref="SelectedValue"/> property
         /// </summary>
         [AssignBinding]
+        [InheritDataTypeFromItems(nameof(ItemsSource))]
         [InheritDataTypeFromItems(nameof(Items))]
         public IBinding? SelectedValueBinding
         {
@@ -322,7 +328,7 @@ namespace Avalonia.Controls.Primitives
                 }
                 else if (_selection != value)
                 {
-                    if (value.Source != null && value.Source != Items)
+                    if (value.Source != null && value.Source != ItemsView.Source)
                     {
                         throw new ArgumentException(
                             "The supplied ISelectionModel already has an assigned Source but this " +
@@ -434,10 +440,9 @@ namespace Avalonia.Controls.Primitives
             return null;
         }
 
-        /// <inheritdoc />
-        protected override void ItemsCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
+        private protected override void OnItemsViewCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
         {
-            base.ItemsCollectionChanged(sender!, e);
+            base.OnItemsViewCollectionChanged(sender!, e);
 
             if (AlwaysSelected && SelectedIndex == -1 && ItemCount > 0)
             {
@@ -547,7 +552,7 @@ namespace Avalonia.Controls.Primitives
 
             if (_selection is object)
             {
-                _selection.Source = Items;
+                _selection.Source = ItemsView.Source;
             }
         }
 
@@ -635,16 +640,6 @@ namespace Avalonia.Controls.Primitives
             {
                 AutoScrollToSelectedItemIfNecessary();
             }
-            if (change.Property == ItemsProperty && _updateState is null && _selection is object)
-            {
-                var newValue = change.GetNewValue<IEnumerable?>();
-                _selection.Source = newValue;
-
-                if (newValue is null)
-                {
-                    _selection.Clear();
-                }
-            }
             else if (change.Property == SelectionModeProperty && _selection is object)
             {
                 var newValue = change.GetNewValue<SelectionMode>();
@@ -880,6 +875,12 @@ namespace Avalonia.Controls.Primitives
             return false;
         }
 
+        private void OnItemsViewSourceChanged(object? sender, EventArgs e)
+        {
+            if (_selection is not null && _updateState is null)
+                _selection.Source = ItemsView.Source;
+        }
+
         /// <summary>
         /// Called when <see cref="INotifyPropertyChanged.PropertyChanged"/> is raised on
         /// <see cref="Selection"/>.
@@ -968,7 +969,7 @@ namespace Avalonia.Controls.Primitives
         /// <param name="e">The event args.</param>
         private void OnSelectionModelLostSelection(object? sender, EventArgs e)
         {
-            if (AlwaysSelected && Items is object)
+            if (AlwaysSelected && ItemsView.Count > 0)
             {
                 SelectedIndex = 0;
             }
@@ -998,14 +999,14 @@ namespace Avalonia.Controls.Primitives
             }
         }
 
-        private object FindItemWithValue(object? value)
+        private object? FindItemWithValue(object? value)
         {
             if (ItemCount == 0 || value is null)
             {
                 return AvaloniaProperty.UnsetValue;
             }
 
-            var items = Items;
+            var items = ItemsView;
             var binding = SelectedValueBinding;
 
             if (binding is null)
@@ -1169,7 +1170,7 @@ namespace Avalonia.Controls.Primitives
         {
             if (_updateState is null)
             {
-                model.Source = Items;
+                model.Source = ItemsView.Source;
             }
 
             model.PropertyChanged += OnSelectionModelPropertyChanged;
@@ -1231,16 +1232,18 @@ namespace Avalonia.Controls.Primitives
                     Selection = state.Selection.Value;
                 }
 
-                if (state.SelectedItems.HasValue)
+                if (_selection is InternalSelectionModel s)
                 {
-                    SelectedItems = state.SelectedItems.Value;
+                    s.Update(ItemsView.Source, state.SelectedItems);
                 }
-
-                Selection.Source = Items;
-
-                if (Items is null)
+                else
                 {
-                    Selection.Clear();
+                    if (state.SelectedItems.HasValue)
+                    {
+                        SelectedItems = state.SelectedItems.Value;
+                    }
+
+                    Selection.Source = ItemsView.Source;
                 }
 
                 if (state.SelectedValue.HasValue)
diff --git a/src/Avalonia.Controls/SelectableTextBlock.cs b/src/Avalonia.Controls/SelectableTextBlock.cs
index 6603e20a2a..1007001f05 100644
--- a/src/Avalonia.Controls/SelectableTextBlock.cs
+++ b/src/Avalonia.Controls/SelectableTextBlock.cs
@@ -17,17 +17,11 @@ namespace Avalonia.Controls
     /// </summary>
     public class SelectableTextBlock : TextBlock, IInlineHost
     {
-        public static readonly DirectProperty<SelectableTextBlock, int> SelectionStartProperty =
-            AvaloniaProperty.RegisterDirect<SelectableTextBlock, int>(
-                nameof(SelectionStart),
-                o => o.SelectionStart,
-                (o, v) => o.SelectionStart = v);
-
-        public static readonly DirectProperty<SelectableTextBlock, int> SelectionEndProperty =
-            AvaloniaProperty.RegisterDirect<SelectableTextBlock, int>(
-                nameof(SelectionEnd),
-                o => o.SelectionEnd,
-                (o, v) => o.SelectionEnd = v);
+        public static readonly StyledProperty<int> SelectionStartProperty =
+            TextBox.SelectionStartProperty.AddOwner<SelectableTextBlock>(new(coerce: TextBox.CoerceCaretIndex));
+
+        public static readonly StyledProperty<int> SelectionEndProperty =
+            TextBox.SelectionEndProperty.AddOwner<SelectableTextBlock>(new(coerce: TextBox.CoerceCaretIndex));
 
         public static readonly DirectProperty<SelectableTextBlock, string> SelectedTextProperty =
             AvaloniaProperty.RegisterDirect<SelectableTextBlock, string>(
@@ -35,21 +29,16 @@ namespace Avalonia.Controls
                 o => o.SelectedText);
 
         public static readonly StyledProperty<IBrush?> SelectionBrushProperty =
-            AvaloniaProperty.Register<SelectableTextBlock, IBrush?>(nameof(SelectionBrush), Brushes.Blue);
-
+            TextBox.SelectionBrushProperty.AddOwner<SelectableTextBlock>(new(new Data.Optional<IBrush?>(Brushes.Blue)));
 
         public static readonly DirectProperty<SelectableTextBlock, bool> CanCopyProperty =
-            AvaloniaProperty.RegisterDirect<SelectableTextBlock, bool>(
-                nameof(CanCopy),
-                o => o.CanCopy);
+            TextBox.CanCopyProperty.AddOwner<SelectableTextBlock>(o => o.CanCopy);
 
         public static readonly RoutedEvent<RoutedEventArgs> CopyingToClipboardEvent =
             RoutedEvent.Register<SelectableTextBlock, RoutedEventArgs>(
                 nameof(CopyingToClipboard), RoutingStrategies.Bubble);
 
         private bool _canCopy;
-        private int _selectionStart;
-        private int _selectionEnd;
         private int _wordSelectionStart = -1;
 
         static SelectableTextBlock()
@@ -78,16 +67,8 @@ namespace Avalonia.Controls
         /// </summary>
         public int SelectionStart
         {
-            get => _selectionStart;
-            set
-            {
-                if (SetAndRaise(SelectionStartProperty, ref _selectionStart, value))
-                {
-                    RaisePropertyChanged(SelectedTextProperty, "", "");
-
-                    UpdateCommandStates();
-                }
-            }
+            get => GetValue(SelectionStartProperty);
+            set => SetValue(SelectionStartProperty, value);
         }
 
         /// <summary>
@@ -95,16 +76,8 @@ namespace Avalonia.Controls
         /// </summary>
         public int SelectionEnd
         {
-            get => _selectionEnd;
-            set
-            {
-                if (SetAndRaise(SelectionEndProperty, ref _selectionEnd, value))
-                {
-                    RaisePropertyChanged(SelectedTextProperty, "", "");
-
-                    UpdateCommandStates();
-                }
-            }
+            get => GetValue(SelectionEndProperty);
+            set => SetValue(SelectionEndProperty, value);
         }
 
         /// <summary>
@@ -150,7 +123,7 @@ namespace Avalonia.Controls
                 await ((IClipboard)AvaloniaLocator.Current.GetRequiredService(typeof(IClipboard)))
                     .SetTextAsync(text);
             }
-        }        
+        }
 
         /// <summary>
         /// Select all text in the TextBox
@@ -159,8 +132,8 @@ namespace Avalonia.Controls
         {
             var text = Text;
 
-            SelectionStart = 0;
-            SelectionEnd = text?.Length ?? 0;
+            SetCurrentValue(SelectionStartProperty, 0);
+            SetCurrentValue(SelectionEndProperty, text?.Length ?? 0);
         }
 
         /// <summary>
@@ -168,7 +141,7 @@ namespace Avalonia.Controls
         /// </summary>
         public void ClearSelection()
         {
-            SelectionEnd = SelectionStart;
+            SetCurrentValue(SelectionEndProperty, SelectionStart);
         }
 
         protected override void OnGotFocus(GotFocusEventArgs e)
@@ -204,7 +177,7 @@ namespace Avalonia.Controls
 
                 var rects = TextLayout.HitTestTextRange(start, length);
 
-                using (context.PushPostTransform(Matrix.CreateTranslation(origin)))
+                using (context.PushTransform(Matrix.CreateTranslation(origin)))
                 {
                     foreach (var rect in rects)
                     {
@@ -240,6 +213,17 @@ namespace Avalonia.Controls
             e.Handled = handled;
         }
 
+        protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
+        {
+            base.OnPropertyChanged(change);
+
+            if (change.Property == SelectionStartProperty || change.Property == SelectionEndProperty)
+            {
+                RaisePropertyChanged(SelectedTextProperty, "", "");
+                UpdateCommandStates();
+            }
+        }
+
         protected override void OnPointerPressed(PointerPressedEventArgs e)
         {
             base.OnPointerPressed(e);
@@ -271,25 +255,26 @@ namespace Avalonia.Controls
 
                                 if (index > _wordSelectionStart)
                                 {
-                                    SelectionEnd = StringUtils.NextWord(text, index);
+                                    SetCurrentValue(SelectionEndProperty, StringUtils.NextWord(text, index));
                                 }
 
                                 if (index < _wordSelectionStart || previousWord == _wordSelectionStart)
                                 {
-                                    SelectionStart = previousWord;
+                                    SetCurrentValue(SelectionStartProperty, previousWord);
                                 }
                             }
                             else
                             {
-                                SelectionStart = Math.Min(oldIndex, index);
-                                SelectionEnd = Math.Max(oldIndex, index);
+                                SetCurrentValue(SelectionStartProperty, Math.Min(oldIndex, index));
+                                SetCurrentValue(SelectionEndProperty, Math.Max(oldIndex, index));
                             }
                         }
                         else
                         {
                             if (_wordSelectionStart == -1 || index < SelectionStart || index > SelectionEnd)
                             {
-                                SelectionStart = SelectionEnd = index;
+                                SetCurrentValue(SelectionStartProperty, index);
+                                SetCurrentValue(SelectionEndProperty, index);
 
                                 _wordSelectionStart = -1;
                             }
@@ -299,16 +284,16 @@ namespace Avalonia.Controls
                     case 2:
                         if (!StringUtils.IsStartOfWord(text, index))
                         {
-                            SelectionStart = StringUtils.PreviousWord(text, index);
+                            SetCurrentValue(SelectionStartProperty, StringUtils.PreviousWord(text, index));
                         }
 
                         _wordSelectionStart = SelectionStart;
 
                         if (!StringUtils.IsEndOfWord(text, index))
                         {
-                            SelectionEnd = StringUtils.NextWord(text, index);
+                            SetCurrentValue(SelectionEndProperty, StringUtils.NextWord(text, index));
                         }
-                        
+
                         break;
                     case 3:
                         _wordSelectionStart = -1;
@@ -347,22 +332,22 @@ namespace Avalonia.Controls
 
                     if (distance <= 0)
                     {
-                        SelectionStart = StringUtils.PreviousWord(text, textPosition);
+                        SetCurrentValue(SelectionStartProperty, StringUtils.PreviousWord(text, textPosition));
                     }
 
                     if (distance >= 0)
                     {
                         if (SelectionStart != _wordSelectionStart)
                         {
-                            SelectionStart = _wordSelectionStart;
+                            SetCurrentValue(SelectionStartProperty, _wordSelectionStart);
                         }
 
-                        SelectionEnd = StringUtils.NextWord(text, textPosition);
+                        SetCurrentValue(SelectionEndProperty, StringUtils.NextWord(text, textPosition));
                     }
                 }
                 else
                 {
-                    SelectionEnd = textPosition;
+                    SetCurrentValue(SelectionEndProperty, textPosition);
                 }
 
             }
@@ -395,7 +380,8 @@ namespace Avalonia.Controls
                                           caretIndex >= firstSelection && caretIndex <= lastSelection;
                 if (!didClickInSelection)
                 {
-                    SelectionStart = SelectionEnd = caretIndex;
+                    SetCurrentValue(SelectionStartProperty, caretIndex);
+                    SetCurrentValue(SelectionEndProperty, caretIndex);
                 }
             }
 
@@ -411,9 +397,8 @@ namespace Avalonia.Controls
 
         private string GetSelection()
         {
-            var text = GetText();
-
-            if (string.IsNullOrEmpty(text))
+            var textLength = Text?.Length ?? 0;
+            if (textLength == 0)
             {
                 return "";
             }
@@ -423,14 +408,14 @@ namespace Avalonia.Controls
             var start = Math.Min(selectionStart, selectionEnd);
             var end = Math.Max(selectionStart, selectionEnd);
 
-            if (start == end || text.Length < end)
+            if (start == end || textLength < end)
             {
                 return "";
             }
 
             var length = Math.Max(0, end - start);
 
-            var selectedText = text.Substring(start, length);
+            var selectedText = Text!.Substring(start, length);
 
             return selectedText;
         }
diff --git a/src/Avalonia.Controls/Selection/InternalSelectionModel.cs b/src/Avalonia.Controls/Selection/InternalSelectionModel.cs
index d0e6144f59..c8ad9bd88b 100644
--- a/src/Avalonia.Controls/Selection/InternalSelectionModel.cs
+++ b/src/Avalonia.Controls/Selection/InternalSelectionModel.cs
@@ -5,6 +5,7 @@ using System.Collections.Specialized;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using Avalonia.Collections;
+using Avalonia.Data;
 
 namespace Avalonia.Controls.Selection
 {
@@ -13,6 +14,7 @@ namespace Avalonia.Controls.Selection
         private IList? _writableSelectedItems;
         private int _ignoreModelChanges;
         private bool _ignoreSelectedItemsChanges;
+        private bool _skipSyncFromSelectedItems;
         private bool _isResetting;
 
         public InternalSelectionModel()
@@ -60,6 +62,29 @@ namespace Avalonia.Controls.Selection
             }
         }
 
+        internal void Update(IEnumerable? source, Optional<IList?> selectedItems)
+        {
+            var previousSource = Source;
+            var previousWritableSelectedItems = _writableSelectedItems;
+
+            try
+            {
+                _skipSyncFromSelectedItems = true;
+                SetSource(source);
+                if (selectedItems.HasValue)
+                    WritableSelectedItems = selectedItems.Value;
+            }
+            finally 
+            { 
+                _skipSyncFromSelectedItems = false;
+            }
+
+            // We skipped the sync from WritableSelectedItems before; do it now that both
+            // the source and WritableSelectedItems are updated.
+            if (previousSource != Source || previousWritableSelectedItems != _writableSelectedItems)
+                SyncFromSelectedItems();
+        }
+
         private protected override void SetSource(IEnumerable? value)
         {
             if (Source == value)
@@ -121,7 +146,7 @@ namespace Avalonia.Controls.Selection
 
         private void SyncFromSelectedItems()
         {
-            if (Source is null || _writableSelectedItems is null)
+            if (_skipSyncFromSelectedItems || Source is null || _writableSelectedItems is null)
             {
                 return;
             }
diff --git a/src/Avalonia.Controls/Selection/SelectionModel.cs b/src/Avalonia.Controls/Selection/SelectionModel.cs
index d4c2b32974..68bad598d0 100644
--- a/src/Avalonia.Controls/Selection/SelectionModel.cs
+++ b/src/Avalonia.Controls/Selection/SelectionModel.cs
@@ -30,9 +30,9 @@ namespace Avalonia.Controls.Selection
             Source = source;
         }
 
-        public new IEnumerable<T>? Source
+        public new IEnumerable? Source
         {
-            get => base.Source as IEnumerable<T>;
+            get => base.Source;
             set => SetSource(value);
         }
 
diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index e790578675..7f10c632c5 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -172,7 +172,7 @@ namespace Avalonia.Controls
                 flyout.Opened += Flyout_Opened;
                 flyout.Closed += Flyout_Closed;
 
-                _flyoutPropertyChangedDisposable = flyout.GetPropertyChangedObservable(Popup.PlacementModeProperty).Subscribe(Flyout_PlacementPropertyChanged);
+                _flyoutPropertyChangedDisposable = flyout.GetPropertyChangedObservable(Popup.PlacementProperty).Subscribe(Flyout_PlacementPropertyChanged);
             }
         }
 
diff --git a/src/Avalonia.Controls/TextBlock.cs b/src/Avalonia.Controls/TextBlock.cs
index df98d1073e..b55ae74965 100644
--- a/src/Avalonia.Controls/TextBlock.cs
+++ b/src/Avalonia.Controls/TextBlock.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using Avalonia.Automation.Peers;
 using Avalonia.Controls.Documents;
 using Avalonia.Layout;
@@ -13,6 +14,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// A control that displays a block of text.
     /// </summary>
+    [DebuggerDisplay("Text = {" + nameof(DebugText) + "}")]
     public class TextBlock : Control, IInlineHost
     {
         /// <summary>
@@ -103,11 +105,8 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="Text"/> property.
         /// </summary>
-        public static readonly DirectProperty<TextBlock, string?> TextProperty =
-            AvaloniaProperty.RegisterDirect<TextBlock, string?>(
-                nameof(Text),
-                o => o.GetText(),
-                (o, v) => o.SetText(v));
+        public static readonly StyledProperty<string?> TextProperty =
+            AvaloniaProperty.Register<TextBlock, string?>(nameof(Text));
 
         /// <summary>
         /// Defines the <see cref="TextAlignment"/> property.
@@ -142,14 +141,14 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="Inlines"/> property.
         /// </summary>
-        public static readonly StyledProperty<InlineCollection?> InlinesProperty =
-            AvaloniaProperty.Register<TextBlock, InlineCollection?>(
-                nameof(Inlines));
+        public static readonly DirectProperty<TextBlock, InlineCollection?> InlinesProperty =
+            AvaloniaProperty.RegisterDirect<TextBlock, InlineCollection?>(
+                nameof(Inlines), t => t.Inlines, (t, v) => t.Inlines = v);
 
-        internal string? _text;
         protected TextLayout? _textLayout;
         protected Size _constraint;
         private IReadOnlyList<TextRun>? _textRuns;
+        private InlineCollection? _inlines;
 
         /// <summary>
         /// Initializes static members of the <see cref="TextBlock"/> class.
@@ -173,7 +172,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Gets the <see cref="TextLayout"/> used to render the text.
         /// </summary>
-        public TextLayout TextLayout => _textLayout ??= CreateTextLayout(_text);
+        public TextLayout TextLayout => _textLayout ??= CreateTextLayout(Text);
 
         /// <summary>
         /// Gets or sets the padding to place around the <see cref="Text"/>.
@@ -198,10 +197,12 @@ namespace Avalonia.Controls
         /// </summary>
         public string? Text
         {
-            get => GetText();
-            set => SetText(value);
+            get => GetValue(TextProperty);
+            set => SetValue(TextProperty, value);
         }
 
+        private string? DebugText => Text ?? Inlines?.Text;
+
         /// <summary>
         /// Gets or sets the font family used to draw the control's text.
         /// </summary>
@@ -325,8 +326,8 @@ namespace Avalonia.Controls
         [Content]
         public InlineCollection? Inlines
         {
-            get => GetValue(InlinesProperty);
-            set => SetValue(InlinesProperty, value);
+            get => _inlines;
+            set => SetAndRaise(InlinesProperty, ref _inlines, value);
         }
 
         protected override bool BypassFlowDirectionPolicies => true;
@@ -590,19 +591,18 @@ namespace Avalonia.Controls
             TextLayout.Draw(context, origin);
         }
 
-        protected virtual string? GetText()
-        {
-            return _text ?? Inlines?.Text;
-        }
-
-        protected virtual void SetText(string? text)
+        private bool _clearTextInternal;
+        internal void ClearTextInternal()
         {
-            if (HasComplexContent)
+            _clearTextInternal = true;
+            try
+            {
+                SetCurrentValue(TextProperty, null);
+            }
+            finally
             {
-                Inlines?.Clear();
+                _clearTextInternal = false;
             }
-           
-            SetAndRaise(TextProperty, ref _text, text);           
         }
 
         /// <summary>
@@ -780,6 +780,14 @@ namespace Avalonia.Controls
         {
             base.OnPropertyChanged(change);
 
+            if (change.Property == TextProperty)
+            {
+                if (HasComplexContent && !_clearTextInternal)
+                {
+                    Inlines?.Clear();
+                }
+            }
+
             switch (change.Property.Name)
             {
                 case nameof(FontSize):
@@ -794,10 +802,10 @@ namespace Avalonia.Controls
 
                 case nameof(FlowDirection):
 
-                case nameof (Padding):
-                case nameof (LineHeight):
-                case nameof (LetterSpacing):
-                case nameof (MaxLines):
+                case nameof(Padding):
+                case nameof(LineHeight):
+                case nameof(LetterSpacing):
+                case nameof(MaxLines):
 
                 case nameof(Text):
                 case nameof(TextDecorations):
@@ -899,7 +907,7 @@ namespace Avalonia.Controls
                         continue;
                     }
 
-                    if (textRun is TextCharacters)                 
+                    if (textRun is TextCharacters)
                     {
                         var skip = Math.Max(0, textSourceIndex - currentPosition);
 
diff --git a/src/Avalonia.Controls/TextBox.cs b/src/Avalonia.Controls/TextBox.cs
index ac1b5cd417..d244290c89 100644
--- a/src/Avalonia.Controls/TextBox.cs
+++ b/src/Avalonia.Controls/TextBox.cs
@@ -61,11 +61,9 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="CaretIndex"/> property
         /// </summary>
-        public static readonly DirectProperty<TextBox, int> CaretIndexProperty =
-            AvaloniaProperty.RegisterDirect<TextBox, int>(
-                nameof(CaretIndex),
-                o => o.CaretIndex,
-                (o, v) => o.CaretIndex = v);
+        public static readonly StyledProperty<int> CaretIndexProperty =
+            AvaloniaProperty.Register<TextBox, int>(nameof(CaretIndex),
+                coerce: CoerceCaretIndex);
 
         /// <summary>
         /// Defines the <see cref="IsReadOnly"/> property
@@ -100,42 +98,37 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="SelectionStart"/> property
         /// </summary>
-        public static readonly DirectProperty<TextBox, int> SelectionStartProperty =
-            AvaloniaProperty.RegisterDirect<TextBox, int>(
-                nameof(SelectionStart),
-                o => o.SelectionStart,
-                (o, v) => o.SelectionStart = v);
+        public static readonly StyledProperty<int> SelectionStartProperty =
+            AvaloniaProperty.Register<TextBox, int>(nameof(SelectionStart), 
+                coerce: CoerceCaretIndex);
 
         /// <summary>
         /// Defines the <see cref="SelectionEnd"/> property
         /// </summary>
-        public static readonly DirectProperty<TextBox, int> SelectionEndProperty =
-            AvaloniaProperty.RegisterDirect<TextBox, int>(
-                nameof(SelectionEnd),
-                o => o.SelectionEnd,
-                (o, v) => o.SelectionEnd = v);
+        public static readonly StyledProperty<int> SelectionEndProperty =
+            AvaloniaProperty.Register<TextBox, int>(nameof(SelectionEnd),
+                coerce: CoerceCaretIndex);
 
         /// <summary>
         /// Defines the <see cref="MaxLength"/> property
         /// </summary>
         public static readonly StyledProperty<int> MaxLengthProperty =
-            AvaloniaProperty.Register<TextBox, int>(nameof(MaxLength), defaultValue: 0);
+            AvaloniaProperty.Register<TextBox, int>(nameof(MaxLength));
 
         /// <summary>
         /// Defines the <see cref="MaxLines"/> property
         /// </summary>
         public static readonly StyledProperty<int> MaxLinesProperty =
-            AvaloniaProperty.Register<TextBox, int>(nameof(MaxLines), defaultValue: 0);
+            AvaloniaProperty.Register<TextBox, int>(nameof(MaxLines));
 
         /// <summary>
         /// Defines the <see cref="Text"/> property
         /// </summary>
-        public static readonly DirectProperty<TextBox, string?> TextProperty =
-            TextBlock.TextProperty.AddOwnerWithDataValidation<TextBox>(
-                o => o.Text,
-                (o, v) => o.Text = v,
+        public static readonly StyledProperty<string?> TextProperty =
+            TextBlock.TextProperty.AddOwner<TextBox>(new(
+                coerce: CoerceText,
                 defaultBindingMode: BindingMode.TwoWay,
-                enableDataValidation: true);
+                enableDataValidation: true));
 
         /// <summary>
         /// Defines the <see cref="TextAlignment"/> property
@@ -185,9 +178,8 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="NewLine"/> property
         /// </summary>
-        public static readonly DirectProperty<TextBox, string> NewLineProperty =
-            AvaloniaProperty.RegisterDirect<TextBox, string>(nameof(NewLine),
-                textbox => textbox.NewLine, (textbox, newline) => textbox.NewLine = newline);
+        public static readonly StyledProperty<string> NewLineProperty =
+            AvaloniaProperty.Register<TextBox, string>(nameof(NewLine), Environment.NewLine);
 
         /// <summary>
         /// Defines the <see cref="InnerLeftContent"/> property
@@ -242,12 +234,8 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="UndoLimit"/> property
         /// </summary>
-        public static readonly DirectProperty<TextBox, int> UndoLimitProperty =
-            AvaloniaProperty.RegisterDirect<TextBox, int>(
-                nameof(UndoLimit),
-                o => o.UndoLimit,
-                (o, v) => o.UndoLimit = v,
-                unsetValue: -1);
+        public static readonly StyledProperty<int> UndoLimitProperty =
+            AvaloniaProperty.Register<TextBox, int>(nameof(UndoLimit), UndoRedoHelper<UndoRedoState>.DefaultUndoLimit);
 
         /// <summary>
         /// Defines the <see cref="CanUndo"/> property
@@ -318,18 +306,13 @@ namespace Avalonia.Controls
             public override int GetHashCode() => Text?.GetHashCode() ?? 0;
         }
 
-        private string? _text;
-        private int _caretIndex;
-        private int _selectionStart;
-        private int _selectionEnd;
         private TextPresenter? _presenter;
-        private TextBoxTextInputMethodClient _imClient = new TextBoxTextInputMethodClient();
-        private UndoRedoHelper<UndoRedoState> _undoRedoHelper;
+        private readonly TextBoxTextInputMethodClient _imClient = new();
+        private readonly UndoRedoHelper<UndoRedoState> _undoRedoHelper;
         private bool _isUndoingRedoing;
         private bool _canCut;
         private bool _canCopy;
         private bool _canPaste;
-        private string _newLine = Environment.NewLine;
         private static readonly string[] invalidCharacters = new String[1] { "\u007f" };
         private bool _canUndo;
         private bool _canRedo;
@@ -399,18 +382,19 @@ namespace Avalonia.Controls
         /// </summary>
         public int CaretIndex
         {
-            get => _caretIndex;
-            set
-            {
-                value = CoerceCaretIndex(value);
-                SetAndRaise(CaretIndexProperty, ref _caretIndex, value);
+            get => GetValue(CaretIndexProperty);
+            set => SetValue(CaretIndexProperty, value);
+        }
 
-                UndoRedoState state;
-                if (IsUndoEnabled && _undoRedoHelper.TryGetLastState(out state) && state.Text == Text)
-                    _undoRedoHelper.UpdateLastState();
+        private void OnCaretIndexChanged(AvaloniaPropertyChangedEventArgs e)
+        {
+            UndoRedoState state;
+            if (IsUndoEnabled && _undoRedoHelper.TryGetLastState(out state) && state.Text == Text)
+                _undoRedoHelper.UpdateLastState();
 
-                SelectionStart = SelectionEnd = value;
-            }
+            var newValue = e.GetNewValue<int>();
+            SetCurrentValue(SelectionStartProperty, newValue);
+            SetCurrentValue(SelectionEndProperty, newValue);
         }
 
         /// <summary>
@@ -463,21 +447,18 @@ namespace Avalonia.Controls
         /// </summary>
         public int SelectionStart
         {
-            get => _selectionStart;
-            set
-            {
-                value = CoerceCaretIndex(value);
-                var changed = SetAndRaise(SelectionStartProperty, ref _selectionStart, value);
+            get => GetValue(SelectionStartProperty);
+            set => SetValue(SelectionStartProperty, value);
+        }
 
-                if (changed)
-                {
-                    UpdateCommandStates();
-                }
+        private void OnSelectionStartChanged(AvaloniaPropertyChangedEventArgs e)
+        {
+            UpdateCommandStates();
 
-                if (SelectionEnd == value && CaretIndex != value)
-                {
-                    CaretIndex = value;
-                }
+            var value = e.GetNewValue<int>();
+            if (SelectionEnd == value && CaretIndex != value)
+            {
+                SetCurrentValue(CaretIndexProperty, value);
             }
         }
 
@@ -490,21 +471,18 @@ namespace Avalonia.Controls
         /// </remarks>
         public int SelectionEnd
         {
-            get => _selectionEnd;
-            set
-            {
-                value = CoerceCaretIndex(value);
-                var changed = SetAndRaise(SelectionEndProperty, ref _selectionEnd, value);
-
-                if (changed)
-                {
-                    UpdateCommandStates();
-                }
+            get => GetValue(SelectionEndProperty);
+            set => SetValue(SelectionEndProperty, value);
+        }
+        
+        private void OnSelectionEndChanged(AvaloniaPropertyChangedEventArgs e)
+        {
+            UpdateCommandStates();
 
-                if (SelectionStart == value && CaretIndex != value)
-                {
-                    CaretIndex = value;
-                }
+            var value = e.GetNewValue<int>();
+            if (SelectionStart == value && CaretIndex != value)
+            {
+                SetCurrentValue(CaretIndexProperty, value);
             }
         }
         
@@ -550,36 +528,27 @@ namespace Avalonia.Controls
         [Content]
         public string? Text
         {
-            get => _text;
-            set
-            {
-                var caretIndex = CaretIndex;
-                var selectionStart = SelectionStart;
-                var selectionEnd = SelectionEnd;
-
-                CaretIndex = CoerceCaretIndex(caretIndex, value);
-                SelectionStart = CoerceCaretIndex(selectionStart, value);
-                SelectionEnd = CoerceCaretIndex(selectionEnd, value);
-
-                // Before #9490, snapshot here was done AFTER text change - this doesn't make sense
-                // since intial state would never be no text and you'd always have to make a text 
-                // change before undo would be available
-                // The undo/redo stacks were also cleared at this point, which also doesn't make sense
-                // as it is still valid to want to undo a programmatic text set
-                // So we snapshot text now BEFORE the change so we can always revert
-                // Also don't need to check IsUndoEnabled here, that's done in SnapshotUndoRedo
-                if (!_isUndoingRedoing)
-                {
-                    SnapshotUndoRedo();
-                }
-
-                var textChanged = SetAndRaise(TextProperty, ref _text, value);
+            get => GetValue(TextProperty);
+            set => SetValue(TextProperty, value);
+        }
 
-                if (textChanged)
-                {
-                    RaiseTextChangeEvents();
-                }
+        private static string? CoerceText(AvaloniaObject sender, string? value)
+        {
+            var textBox = (TextBox)sender;
+            
+            // Before #9490, snapshot here was done AFTER text change - this doesn't make sense
+            // since intial state would never be no text and you'd always have to make a text 
+            // change before undo would be available
+            // The undo/redo stacks were also cleared at this point, which also doesn't make sense
+            // as it is still valid to want to undo a programmatic text set
+            // So we snapshot text now BEFORE the change so we can always revert
+            // Also don't need to check IsUndoEnabled here, that's done in SnapshotUndoRedo
+            if (!textBox._isUndoingRedoing)
+            {
+                textBox.SnapshotUndoRedo();
             }
+
+            return value;
         }
 
         /// <summary>
@@ -691,8 +660,8 @@ namespace Avalonia.Controls
         /// </summary>
         public string NewLine
         {
-            get => _newLine;
-            set => SetAndRaise(NewLineProperty, ref _newLine, value);
+            get => GetValue(NewLineProperty);
+            set => SetValue(NewLineProperty, value);
         }
 
         /// <summary>
@@ -700,7 +669,8 @@ namespace Avalonia.Controls
         /// </summary>
         public void ClearSelection()
         {
-            CaretIndex = SelectionStart;
+            SetCurrentValue(CaretIndexProperty, SelectionStart);
+            SetCurrentValue(SelectionEndProperty, SelectionStart);
         }
 
         /// <summary>
@@ -744,25 +714,20 @@ namespace Avalonia.Controls
         /// </summary>
         public int UndoLimit
         {
-            get => _undoRedoHelper.Limit;
-            set
-            {
-                if (_undoRedoHelper.Limit != value)
-                {
-                    // can't use SetAndRaise due to using _undoRedoHelper.Limit
-                    // (can't send a ref of a property to SetAndRaise),
-                    // so use RaisePropertyChanged instead.
-                    var oldValue = _undoRedoHelper.Limit;
-                    _undoRedoHelper.Limit = value;
-                    RaisePropertyChanged(UndoLimitProperty, oldValue, value);
-                }
-                // from docs at
-                // https://docs.microsoft.com/en-us/dotnet/api/system.windows.controls.primitives.textboxbase.isundoenabled:
-                // "Setting UndoLimit clears the undo queue."
-                _undoRedoHelper.Clear();
-                _selectedTextChangesMadeSinceLastUndoSnapshot = 0;
-                _hasDoneSnapshotOnce = false;
-            }
+            get => GetValue(UndoLimitProperty);
+            set => SetValue(UndoLimitProperty, value);
+        }
+
+        private void OnUndoLimitChanged(int newValue)
+        {
+            _undoRedoHelper.Limit = newValue;
+
+            // from docs at
+            // https://docs.microsoft.com/en-us/dotnet/api/system.windows.controls.primitives.textboxbase.isundoenabled:
+            // "Setting UndoLimit clears the undo queue."
+            _undoRedoHelper.Clear();
+            _selectedTextChangesMadeSinceLastUndoSnapshot = 0;
+            _hasDoneSnapshotOnce = false;
         }
 
         /// <summary>
@@ -866,9 +831,31 @@ namespace Avalonia.Controls
 
             if (change.Property == TextProperty)
             {
+                CoerceValue(CaretIndexProperty);
+                CoerceValue(SelectionStartProperty);
+                CoerceValue(SelectionEndProperty);
+
+                RaiseTextChangeEvents();
+
                 UpdatePseudoclasses();
                 UpdateCommandStates();
             }
+            else if (change.Property == CaretIndexProperty)
+            {
+                OnCaretIndexChanged(change);
+            }
+            else if (change.Property == SelectionStartProperty)
+            {
+                OnSelectionStartChanged(change);
+            }
+            else if (change.Property == SelectionEndProperty)
+            {
+                OnSelectionEndChanged(change);
+            }
+            else if (change.Property == UndoLimitProperty)
+            {
+                OnUndoLimitChanged(change.GetNewValue<int>());
+            }
             else if (change.Property == IsUndoEnabledProperty && change.GetNewValue<bool>() == false)
             {
                 // from docs at
@@ -920,7 +907,7 @@ namespace Avalonia.Controls
                 (ContextMenu == null || !ContextMenu.IsOpen))
             {
                 ClearSelection();
-                RevealPassword = false;
+                SetCurrentValue(RevealPasswordProperty, false);
             }
 
             UpdateCommandStates();
@@ -986,35 +973,44 @@ namespace Avalonia.Controls
                 }
             }
 
-            var text = Text ?? string.Empty;
-            var newLength = input.Length + text.Length - Math.Abs(SelectionStart - SelectionEnd);
+            var currentText = Text ?? string.Empty;
+            var selectionLength = Math.Abs(SelectionStart - SelectionEnd);
+            var newLength = input.Length + currentText.Length - selectionLength;
 
             if (MaxLength > 0 && newLength > MaxLength)
             {
                 input = input.Remove(Math.Max(0, input.Length - (newLength - MaxLength)));
+                newLength = MaxLength;
             }
 
             if (!string.IsNullOrEmpty(input))
             {
-                var oldText = _text;
-
-                DeleteSelection(false);
+                var textBuilder = StringBuilderCache.Acquire(Math.Max(currentText.Length, newLength));
+                textBuilder.Append(currentText);
+                
                 var caretIndex = CaretIndex;
-                text = Text ?? string.Empty;
-                SetTextInternal(text.Substring(0, caretIndex) + input + text.Substring(caretIndex));
-                ClearSelection();
 
-                if (IsUndoEnabled)
+                if (selectionLength != 0)
                 {
-                    _undoRedoHelper.DiscardRedo();
+                    var (start, _) = GetSelectionRange();
+
+                    textBuilder.Remove(start, selectionLength);
+
+                    caretIndex = start;
                 }
 
-                if (_text != oldText)
+                textBuilder.Insert(caretIndex, input);
+
+                SetCurrentValue(TextProperty, StringBuilderCache.GetStringAndRelease(textBuilder));
+
+                ClearSelection();
+
+                if (IsUndoEnabled)
                 {
-                    RaisePropertyChanged(TextProperty, oldText, _text);
+                    _undoRedoHelper.DiscardRedo();
                 }
 
-                CaretIndex = caretIndex + input.Length;
+                SetCurrentValue(CaretIndexProperty, caretIndex + input.Length);
             }
         }
 
@@ -1168,7 +1164,7 @@ namespace Avalonia.Controls
                 movement = true;
                 selection = false;
                 handled = true;
-                CaretIndex = _presenter.CaretIndex;
+                SetCurrentValue(CaretIndexProperty, _presenter.CaretIndex);
             }
             else if (Match(keymap.MoveCursorToTheEndOfDocument))
             {
@@ -1176,7 +1172,7 @@ namespace Avalonia.Controls
                 movement = true;
                 selection = false;
                 handled = true;
-                CaretIndex = _presenter.CaretIndex;
+                SetCurrentValue(CaretIndexProperty, _presenter.CaretIndex);
             }
             else if (Match(keymap.MoveCursorToTheStartOfLine))
             {
@@ -1184,7 +1180,7 @@ namespace Avalonia.Controls
                 movement = true;
                 selection = false;
                 handled = true;
-                CaretIndex = _presenter.CaretIndex;
+                SetCurrentValue(CaretIndexProperty, _presenter.CaretIndex);
             }
             else if (Match(keymap.MoveCursorToTheEndOfLine))
             {
@@ -1192,31 +1188,31 @@ namespace Avalonia.Controls
                 movement = true;
                 selection = false;
                 handled = true;
-                CaretIndex = _presenter.CaretIndex;
+                SetCurrentValue(CaretIndexProperty, _presenter.CaretIndex);
             }
             else if (Match(keymap.MoveCursorToTheStartOfDocumentWithSelection))
             {
-                SelectionStart = caretIndex;
+                SetCurrentValue(SelectionStartProperty, caretIndex);
                 MoveHome(true);
-                SelectionEnd = _presenter.CaretIndex;
+                SetCurrentValue(SelectionEndProperty, _presenter.CaretIndex);
                 movement = true;
                 selection = true;
                 handled = true;
             }
             else if (Match(keymap.MoveCursorToTheEndOfDocumentWithSelection))
             {
-                SelectionStart = caretIndex;
+                SetCurrentValue(SelectionStartProperty, caretIndex);
                 MoveEnd(true);
-                SelectionEnd = _presenter.CaretIndex;
+                SetCurrentValue(SelectionEndProperty, _presenter.CaretIndex);
                 movement = true;
                 selection = true;
                 handled = true;
             }
             else if (Match(keymap.MoveCursorToTheStartOfLineWithSelection))
             {
-                SelectionStart = caretIndex;
+                SetCurrentValue(SelectionStartProperty, caretIndex);
                 MoveHome(false);
-                SelectionEnd = _presenter.CaretIndex;
+                SetCurrentValue(SelectionEndProperty, _presenter.CaretIndex);
                 movement = true;
                 selection = true;
                 handled = true;
@@ -1224,9 +1220,9 @@ namespace Avalonia.Controls
             }
             else if (Match(keymap.MoveCursorToTheEndOfLineWithSelection))
             {
-                SelectionStart = caretIndex;
+                SetCurrentValue(SelectionStartProperty, caretIndex);
                 MoveEnd(false);
-                SelectionEnd = _presenter.CaretIndex;
+                SetCurrentValue(SelectionEndProperty, _presenter.CaretIndex);
                 movement = true;
                 selection = true;
                 handled = true;
@@ -1261,11 +1257,11 @@ namespace Avalonia.Controls
 
                             if (selection)
                             {
-                                SelectionEnd = _presenter.CaretIndex;
+                                SetCurrentValue(SelectionEndProperty, _presenter.CaretIndex);
                             }
                             else
                             {
-                                CaretIndex = _presenter.CaretIndex;
+                                SetCurrentValue(CaretIndexProperty, _presenter.CaretIndex);
                             }
 
                             break;
@@ -1283,11 +1279,11 @@ namespace Avalonia.Controls
 
                             if (selection)
                             {
-                                SelectionEnd = _presenter.CaretIndex;
+                                SetCurrentValue(SelectionEndProperty, _presenter.CaretIndex);
                             }
                             else
                             {
-                                CaretIndex = _presenter.CaretIndex;
+                                SetCurrentValue(CaretIndexProperty, _presenter.CaretIndex);
                             }
 
                             break;
@@ -1314,11 +1310,13 @@ namespace Avalonia.Controls
 
                                     var length = end - start;
 
-                                    var editedText = text.Substring(0, start) + text.Substring(Math.Min(end, text.Length));
+                                    var sb = StringBuilderCache.Acquire(text.Length);
+                                    sb.Append(text);
+                                    sb.Remove(start, end - start);
 
-                                    SetTextInternal(editedText);
+                                    SetCurrentValue(TextProperty, StringBuilderCache.GetStringAndRelease(sb));
 
-                                    CaretIndex = start;
+                                    SetCurrentValue(CaretIndexProperty, start);
                                 }
                             }
 
@@ -1346,9 +1344,11 @@ namespace Avalonia.Controls
                                 var start = Math.Min(nextPosition, caretIndex);
                                 var end = Math.Max(nextPosition, caretIndex);
 
-                                var editedText = text.Substring(0, start) + text.Substring(Math.Min(end, text.Length));
+                                var sb = StringBuilderCache.Acquire(text.Length);
+                                sb.Append(text);
+                                sb.Remove(start, end - start);
 
-                                SetTextInternal(editedText);
+                                SetCurrentValue(TextProperty, StringBuilderCache.GetStringAndRelease(sb));
                             }
                         }
 
@@ -1425,7 +1425,7 @@ namespace Avalonia.Controls
 
                 var clickToSelect = e.KeyModifiers.HasFlag(KeyModifiers.Shift);
 
-                SetAndRaise(CaretIndexProperty, ref _caretIndex, index);
+                SetCurrentValue(CaretIndexProperty, index);
 
                 switch (e.ClickCount)
                 {
@@ -1438,25 +1438,26 @@ namespace Avalonia.Controls
 
                                 if (index > _wordSelectionStart)
                                 {
-                                    SelectionEnd = StringUtils.NextWord(text, index);
+                                    SetCurrentValue(SelectionEndProperty, StringUtils.NextWord(text, index));
                                 }
 
                                 if (index < _wordSelectionStart || previousWord == _wordSelectionStart)
                                 {
-                                    SelectionStart = previousWord;
+                                    SetCurrentValue(SelectionStartProperty, previousWord);
                                 }
                             }
                             else
                             {
-                                SelectionStart = Math.Min(oldIndex, index);
-                                SelectionEnd = Math.Max(oldIndex, index);
+                                SetCurrentValue(SelectionStartProperty, Math.Min(oldIndex, index));
+                                SetCurrentValue(SelectionEndProperty, Math.Max(oldIndex, index));
                             }
                         }
                         else
                         {
                             if(_wordSelectionStart == -1 || index < SelectionStart || index > SelectionEnd)
                             {
-                                SelectionStart = SelectionEnd = index;
+                                SetCurrentValue(SelectionStartProperty, index);
+                                SetCurrentValue(SelectionEndProperty, index);
                                 _wordSelectionStart = -1;
                             }                           
                         }
@@ -1466,14 +1467,14 @@ namespace Avalonia.Controls
 
                         if (!StringUtils.IsStartOfWord(text, index))
                         {
-                            SelectionStart = StringUtils.PreviousWord(text, index);
+                            SetCurrentValue(SelectionStartProperty, StringUtils.PreviousWord(text, index));
                         }
 
                         _wordSelectionStart = SelectionStart;
 
                         if (!StringUtils.IsEndOfWord(text, index))
                         {
-                            SelectionEnd = StringUtils.NextWord(text, index);
+                            SetCurrentValue(SelectionEndProperty, StringUtils.NextWord(text, index));
                         }
 
                         break;
@@ -1517,22 +1518,22 @@ namespace Avalonia.Controls
 
                     if (distance <= 0)
                     {
-                        SelectionStart = StringUtils.PreviousWord(text, caretIndex);
+                        SetCurrentValue(SelectionStartProperty, StringUtils.PreviousWord(text, caretIndex));
                     }
 
                     if (distance >= 0)
                     {
                         if(SelectionStart != _wordSelectionStart)
                         {
-                            SelectionStart = _wordSelectionStart;
+                            SetCurrentValue(SelectionStartProperty, _wordSelectionStart);
                         }
 
-                        SelectionEnd = StringUtils.NextWord(text, caretIndex);
+                        SetCurrentValue(SelectionEndProperty, StringUtils.NextWord(text, caretIndex));
                     }
                 }
                 else
                 {
-                    SelectionEnd = caretIndex;
+                    SetCurrentValue(SelectionEndProperty, caretIndex);
                 }
             }
         }
@@ -1565,7 +1566,9 @@ namespace Avalonia.Controls
                                           caretIndex >= firstSelection && caretIndex <= lastSelection;
                 if (!didClickInSelection)
                 {
-                    CaretIndex = SelectionEnd = SelectionStart = caretIndex;
+                    SetCurrentValue(CaretIndexProperty, caretIndex);
+                    SetCurrentValue(SelectionEndProperty, caretIndex);
+                    SetCurrentValue(SelectionStartProperty, caretIndex);
                 }
             }
 
@@ -1588,10 +1591,10 @@ namespace Avalonia.Controls
             }
         }
 
-        private int CoerceCaretIndex(int value) => CoerceCaretIndex(value, Text);
-
-        private static int CoerceCaretIndex(int value, string? text)
+        internal static int CoerceCaretIndex(AvaloniaObject sender, int value)
         {
+            var text = sender.GetValue(TextProperty); // method also used by TextPresenter and SelectableTextBlock
+
             if (text == null)
             {
                 return 0;
@@ -1619,10 +1622,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Clears the text in the TextBox
         /// </summary>
-        public void Clear()
-        {
-            Text = string.Empty;
-        }
+        public void Clear() => SetCurrentValue(TextProperty, string.Empty);
 
         private void MoveHorizontal(int direction, bool wholeWord, bool isSelecting)
         {
@@ -1645,7 +1645,7 @@ namespace Avalonia.Controls
                         LogicalDirection.Forward :
                         LogicalDirection.Backward);
 
-                    SelectionEnd = _presenter.CaretIndex;
+                    SetCurrentValue(SelectionEndProperty, _presenter.CaretIndex);
                 }
                 else
                 {
@@ -1662,7 +1662,7 @@ namespace Avalonia.Controls
                             LogicalDirection.Backward);
                     }
 
-                    CaretIndex = _presenter.CaretIndex;
+                    SetCurrentValue(CaretIndexProperty, _presenter.CaretIndex);
                 }
             }
             else
@@ -1678,17 +1678,17 @@ namespace Avalonia.Controls
                     offset = StringUtils.PreviousWord(text, selectionEnd) - selectionEnd;
                 }
 
-                SelectionEnd += offset;
+                SetCurrentValue(SelectionEndProperty, SelectionEnd + offset);
 
                 _presenter.MoveCaretToTextPosition(SelectionEnd);
 
                 if (!isSelecting)
                 {
-                    CaretIndex = SelectionEnd;
+                    SetCurrentValue(CaretIndexProperty, SelectionEnd);
                 }
                 else
                 {
-                    SelectionStart = selectionStart;
+                    SetCurrentValue(SelectionStartProperty, selectionStart);
                 }
             }
         }
@@ -1747,36 +1747,45 @@ namespace Avalonia.Controls
         /// </summary>
         public void SelectAll()
         {
-            SelectionStart = 0;
-            SelectionEnd = Text?.Length ?? 0;
+            SetCurrentValue(SelectionStartProperty, 0);
+            SetCurrentValue(SelectionEndProperty, Text?.Length ?? 0);
         }
 
-        internal bool DeleteSelection(bool raiseTextChanged = true)
+        private (int start, int end) GetSelectionRange()
+        {
+            var selectionStart = SelectionStart;
+            var selectionEnd = SelectionEnd;
+
+            return (Math.Min(selectionStart, selectionEnd), Math.Max(selectionStart, selectionEnd));
+        }
+
+        internal bool DeleteSelection()
         {
             if (IsReadOnly)
                 return true;
 
-            var selectionStart = SelectionStart;
-            var selectionEnd = SelectionEnd;
+            var (start, end) = GetSelectionRange();
 
-            if (selectionStart != selectionEnd)
+            if (start != end)
             {
-                var start = Math.Min(selectionStart, selectionEnd);
-                var end = Math.Max(selectionStart, selectionEnd);
                 var text = Text!;
+                var textBuilder = StringBuilderCache.Acquire(text.Length);
 
-                SetTextInternal(text.Substring(0, start) + text.Substring(end), raiseTextChanged);
+                textBuilder.Append(text);
+                textBuilder.Remove(start, end - start);
+
+                SetCurrentValue(TextProperty, textBuilder.ToString());
 
                 _presenter?.MoveCaretToTextPosition(start);
 
-                CaretIndex = start;
+                SetCurrentValue(CaretIndexProperty, start);
 
                 ClearSelection();
 
                 return true;
             }
 
-            CaretIndex = SelectionStart;
+            SetCurrentValue(CaretIndexProperty, SelectionStart);
 
             return false;
         }
@@ -1826,46 +1835,30 @@ namespace Avalonia.Controls
             }, DispatcherPriority.Normal);
         }
 
-        private void SetTextInternal(string value, bool raiseTextChanged = true)
-        {
-            if (raiseTextChanged)
-            {
-                bool textChanged = SetAndRaise(TextProperty, ref _text, value);
-
-                if (textChanged)
-                {
-                    RaiseTextChangeEvents();
-                }
-            }
-            else
-            {
-                _text = value;
-            }
-        }
-
         private void SetSelectionForControlBackspace()
         {
             var selectionStart = CaretIndex;
 
             MoveHorizontal(-1, true, false);
 
-            SelectionStart = selectionStart;
+            SetCurrentValue(SelectionStartProperty, selectionStart);
         }
 
         private void SetSelectionForControlDelete()
         {
-            if (_text == null || _presenter == null)
+            var textLength = Text?.Length ?? 0;
+            if (_presenter == null || textLength == 0)
             {
                 return;
             }
 
-            SelectionStart = CaretIndex;
+            SetCurrentValue(SelectionStartProperty, CaretIndex);
 
             MoveHorizontal(1, true, true);
 
-            if (SelectionEnd < _text.Length && _text[SelectionEnd] == ' ')
+            if (SelectionEnd < textLength && Text![SelectionEnd] == ' ')
             {
-                SelectionEnd++;
+                SetCurrentValue(SelectionEndProperty, SelectionEnd + 1);
             }
         }
 
@@ -1881,8 +1874,8 @@ namespace Avalonia.Controls
             get => new UndoRedoState(Text, CaretIndex);
             set
             {
-                Text = value.Text;
-                CaretIndex = value.CaretPosition;
+                SetCurrentValue(TextProperty, value.Text);
+                SetCurrentValue(CaretIndexProperty, value.CaretPosition);
                 ClearSelection();
             }
         }
diff --git a/src/Avalonia.Controls/TextBoxTextInputMethodClient.cs b/src/Avalonia.Controls/TextBoxTextInputMethodClient.cs
index deace4084c..e999d0bb74 100644
--- a/src/Avalonia.Controls/TextBoxTextInputMethodClient.cs
+++ b/src/Avalonia.Controls/TextBoxTextInputMethodClient.cs
@@ -106,7 +106,7 @@ namespace Avalonia.Controls
         {
             if (_presenter != null && _textEditable != null)
             {
-                _presenter.CompositionRegion = new TextRange(_textEditable.CompositionStart, _textEditable.CompositionEnd);
+                _presenter.SetCurrentValue(TextPresenter.CompositionRegionProperty, new TextRange(_textEditable.CompositionStart, _textEditable.CompositionEnd));
             }
         }
 
@@ -177,9 +177,9 @@ namespace Avalonia.Controls
 
             var text = GetText(preeditText);
 
-            _presenter._text = text;
+            _presenter.SetCurrentValue(TextPresenter.TextProperty, text);
 
-            _presenter.PreeditText = preeditText;
+            _presenter.SetCurrentValue(TextPresenter.PreeditTextProperty, preeditText);
 
             _presenter.UpdateCaret(new CharacterHit(_compositionStart + (preeditText != null ? preeditText.Length : 0)), false);
 
@@ -201,9 +201,12 @@ namespace Avalonia.Controls
                 return preeditText;
             }
 
-            var text = _presenterText.Substring(0, _compositionStart) + preeditText + _presenterText.Substring(_compositionStart);
+            var sb = StringBuilderCache.Acquire(_presenterText.Length + preeditText.Length);
 
-            return text;
+            sb.Append(_presenterText);
+            sb.Insert(_compositionStart, preeditText);
+
+            return StringBuilderCache.GetStringAndRelease(sb);
         }
 
         public void SetComposingRegion(TextRange? region)
@@ -213,7 +216,7 @@ namespace Avalonia.Controls
                 return;
             }
 
-            _presenter.CompositionRegion = region;
+            _presenter.SetCurrentValue(TextPresenter.CompositionRegionProperty, region);
         }
 
         public void SelectInSurroundingText(int start, int end)
@@ -252,9 +255,9 @@ namespace Avalonia.Controls
 
             if (_presenter != null)
             {
-                _presenter.PreeditText = null;
+                _presenter.ClearValue(TextPresenter.PreeditTextProperty);
 
-                _presenter.CompositionRegion = null;
+                _presenter.ClearValue(TextPresenter.CompositionRegionProperty);
 
                 _presenter.CaretBoundsChanged -= OnCaretBoundsChanged;
             }
diff --git a/src/Avalonia.Controls/TopLevel.cs b/src/Avalonia.Controls/TopLevel.cs
index 5c2a8c8a13..dcf387afab 100644
--- a/src/Avalonia.Controls/TopLevel.cs
+++ b/src/Avalonia.Controls/TopLevel.cs
@@ -15,7 +15,6 @@ using Avalonia.LogicalTree;
 using Avalonia.Media;
 using Avalonia.Platform;
 using Avalonia.Platform.Storage;
-using Avalonia.Reactive;
 using Avalonia.Rendering;
 using Avalonia.Styling;
 using Avalonia.Utilities;
diff --git a/src/Avalonia.Controls/Utils/SelectingItemsControlSelectionAdapter.cs b/src/Avalonia.Controls/Utils/SelectingItemsControlSelectionAdapter.cs
index 3c1b1262ae..5f528e2c72 100644
--- a/src/Avalonia.Controls/Utils/SelectingItemsControlSelectionAdapter.cs
+++ b/src/Avalonia.Controls/Utils/SelectingItemsControlSelectionAdapter.cs
@@ -144,13 +144,13 @@ namespace Avalonia.Controls.Utils
         {
             get
             {
-                return SelectorControl?.Items;
+                return SelectorControl?.ItemsSource;
             }
             set
             {
                 if (SelectorControl != null)
                 {
-                    SelectorControl.Items = value;
+                    SelectorControl.ItemsSource = value;
                 }
             }
         }
diff --git a/src/Avalonia.Controls/Utils/UndoRedoHelper.cs b/src/Avalonia.Controls/Utils/UndoRedoHelper.cs
index 7b663dd017..3452b8bb03 100644
--- a/src/Avalonia.Controls/Utils/UndoRedoHelper.cs
+++ b/src/Avalonia.Controls/Utils/UndoRedoHelper.cs
@@ -4,6 +4,8 @@ namespace Avalonia.Controls.Utils
 {
     class UndoRedoHelper<TState>
     {
+        public const int DefaultUndoLimit = 10;
+
         private readonly IUndoRedoHost _host;
 
         public interface IUndoRedoHost
@@ -23,7 +25,7 @@ namespace Avalonia.Controls.Utils
         /// Maximum number of states this helper can store for undo/redo.
         /// If -1, no limit is imposed.
         /// </summary>
-        public int Limit { get; set; } = 10;
+        public int Limit { get; set; } = DefaultUndoLimit;
 
         public bool CanUndo => _currentNode?.Previous != null;
 
diff --git a/src/Avalonia.Controls/VirtualizingPanel.cs b/src/Avalonia.Controls/VirtualizingPanel.cs
index 7780843eb5..a95d4f1ffa 100644
--- a/src/Avalonia.Controls/VirtualizingPanel.cs
+++ b/src/Avalonia.Controls/VirtualizingPanel.cs
@@ -34,7 +34,8 @@ namespace Avalonia.Controls
         /// <summary>
         /// Gets the items to display.
         /// </summary>
-        protected IReadOnlyList<object?> Items => ItemsControl?.ItemsView ?? ItemsSourceView.Empty;
+        protected IReadOnlyList<object?> Items => (IReadOnlyList<object?>?)ItemsControl?.ItemsView ?? 
+            Array.Empty<object?>();
 
         /// <summary>
         /// Gets the <see cref="ItemsControl"/> that the panel is displaying items for.
@@ -192,17 +193,13 @@ namespace Avalonia.Controls
                 throw new InvalidOperationException("The VirtualizingPanel is already attached to an ItemsControl");
 
             ItemsControl = itemsControl;
-            ItemsControl.PropertyChanged += OnItemsControlPropertyChanged;
             ItemsControl.ItemsView.PostCollectionChanged += OnItemsControlItemsChanged;
         }
 
         internal void Detach()
         {
             var itemsControl = EnsureItemsControl();
-
-            itemsControl.PropertyChanged -= OnItemsControlPropertyChanged;
             itemsControl.ItemsView.PostCollectionChanged -= OnItemsControlItemsChanged;
-
             ItemsControl = null;
             Children.Clear();
         }
@@ -216,20 +213,9 @@ namespace Avalonia.Controls
             return ItemsControl;
         }
 
-        private protected virtual void OnItemsControlPropertyChanged(object? sender, AvaloniaPropertyChangedEventArgs e)
-        {
-            if (e.Property == ItemsControl.ItemsViewProperty)
-            {
-                var (oldValue, newValue) = e.GetOldAndNewValue<ItemsSourceView>();
-                oldValue.PostCollectionChanged -= OnItemsControlItemsChanged;
-                Refresh();
-                newValue.PostCollectionChanged += OnItemsControlItemsChanged;
-            }
-        }
-
         private void OnItemsControlItemsChanged(object? sender, NotifyCollectionChangedEventArgs e)
         {
-            OnItemsChanged(_itemsControl?.ItemsView ?? ItemsSourceView.Empty, e);
+            OnItemsChanged(Items, e);
         }
 
         [DoesNotReturn]
diff --git a/src/Avalonia.Controls/VirtualizingStackPanel.cs b/src/Avalonia.Controls/VirtualizingStackPanel.cs
index 4970a333a5..dfacb93eeb 100644
--- a/src/Avalonia.Controls/VirtualizingStackPanel.cs
+++ b/src/Avalonia.Controls/VirtualizingStackPanel.cs
@@ -459,7 +459,8 @@ namespace Avalonia.Controls
 
             while (c is not null)
             {
-                if (!c.Bounds.IsDefault && c.TransformToVisual(this) is Matrix transform)
+                if ((c.Bounds.Width != 0 || c.Bounds.Height != 0) &&
+                    c.TransformToVisual(this) is Matrix transform)
                 {
                     viewport = new Rect(0, 0, c.Bounds.Width, c.Bounds.Height)
                         .TransformToAABB(transform);
@@ -1078,7 +1079,7 @@ namespace Avalonia.Controls
                     // elements after the insertion point.
                     var elementCount = _elements.Count;
                     var start = Math.Max(realizedIndex, 0);
-                    var newIndex = first + count;
+                    var newIndex = realizedIndex + count;
 
                     for (var i = start; i < elementCount; ++i)
                     {
diff --git a/src/Avalonia.Diagnostics/Diagnostics/Controls/FilterTextBox.cs b/src/Avalonia.Diagnostics/Diagnostics/Controls/FilterTextBox.cs
index 66fad557d5..1e5674cc21 100644
--- a/src/Avalonia.Diagnostics/Diagnostics/Controls/FilterTextBox.cs
+++ b/src/Avalonia.Diagnostics/Diagnostics/Controls/FilterTextBox.cs
@@ -7,23 +7,18 @@ namespace Avalonia.Diagnostics.Controls
 {
     internal class FilterTextBox : TextBox, IStyleable
     {
-        public static readonly DirectProperty<FilterTextBox, bool> UseRegexFilterProperty =
-            AvaloniaProperty.RegisterDirect<FilterTextBox, bool>(nameof(UseRegexFilter),
-                o => o.UseRegexFilter, (o, v) => o.UseRegexFilter = v,
+        public static readonly StyledProperty<bool> UseRegexFilterProperty =
+            AvaloniaProperty.Register<FilterTextBox, bool>(nameof(UseRegexFilter),
                 defaultBindingMode: BindingMode.TwoWay);
 
-        public static readonly DirectProperty<FilterTextBox, bool> UseCaseSensitiveFilterProperty =
-            AvaloniaProperty.RegisterDirect<FilterTextBox, bool>(nameof(UseCaseSensitiveFilter),
-                o => o.UseCaseSensitiveFilter, (o, v) => o.UseCaseSensitiveFilter = v,
+        public static readonly StyledProperty<bool> UseCaseSensitiveFilterProperty =
+            AvaloniaProperty.Register<FilterTextBox, bool>(nameof(UseCaseSensitiveFilter),
                 defaultBindingMode: BindingMode.TwoWay);
 
-        public static readonly DirectProperty<FilterTextBox, bool> UseWholeWordFilterProperty =
-            AvaloniaProperty.RegisterDirect<FilterTextBox, bool>(nameof(UseWholeWordFilter),
-                o => o.UseWholeWordFilter, (o, v) => o.UseWholeWordFilter = v,
+        public static readonly StyledProperty<bool> UseWholeWordFilterProperty =
+            AvaloniaProperty.Register<FilterTextBox, bool>(nameof(UseWholeWordFilter),
                 defaultBindingMode: BindingMode.TwoWay);
 
-        private bool _useRegexFilter, _useCaseSensitiveFilter, _useWholeWordFilter;
-
         public FilterTextBox()
         {
             Classes.Add("filter-text-box");
@@ -31,20 +26,20 @@ namespace Avalonia.Diagnostics.Controls
 
         public bool UseRegexFilter
         {
-            get => _useRegexFilter;
-            set => SetAndRaise(UseRegexFilterProperty, ref _useRegexFilter, value);
+            get => GetValue(UseRegexFilterProperty);
+            set => SetValue(UseRegexFilterProperty, value);
         }
 
         public bool UseCaseSensitiveFilter
         {
-            get => _useCaseSensitiveFilter;
-            set => SetAndRaise(UseCaseSensitiveFilterProperty, ref _useCaseSensitiveFilter, value);
+            get => GetValue(UseCaseSensitiveFilterProperty);
+            set => SetValue(UseCaseSensitiveFilterProperty,value);
         }
 
         public bool UseWholeWordFilter
         {
-            get => _useWholeWordFilter;
-            set => SetAndRaise(UseWholeWordFilterProperty, ref _useWholeWordFilter, value);
+            get => GetValue(UseWholeWordFilterProperty);
+            set => SetValue(UseWholeWordFilterProperty, value);
         }
 
         Type IStyleable.StyleKey => typeof(TextBox);
diff --git a/src/Avalonia.Diagnostics/Diagnostics/Views/ConsoleView.xaml b/src/Avalonia.Diagnostics/Diagnostics/Views/ConsoleView.xaml
index 3bef23a160..dad87f72fd 100644
--- a/src/Avalonia.Diagnostics/Diagnostics/Views/ConsoleView.xaml
+++ b/src/Avalonia.Diagnostics/Diagnostics/Views/ConsoleView.xaml
@@ -40,7 +40,7 @@
              BorderBrush="{DynamicResource ThemeControlMidBrush}"
              BorderThickness="0,0,0,1"
              FontFamily="/Assets/Fonts/SourceSansPro-Regular.ttf"
-             Items="{Binding History}">
+             ItemsSource="{Binding History}">
       <ListBox.ItemTemplate>
         <DataTemplate>
           <StackPanel Orientation="Vertical">
diff --git a/src/Avalonia.Diagnostics/Diagnostics/Views/ControlDetailsView.xaml b/src/Avalonia.Diagnostics/Diagnostics/Views/ControlDetailsView.xaml
index 97f195c91b..c2e63da31c 100644
--- a/src/Avalonia.Diagnostics/Diagnostics/Views/ControlDetailsView.xaml
+++ b/src/Avalonia.Diagnostics/Diagnostics/Views/ControlDetailsView.xaml
@@ -124,7 +124,7 @@
         </Grid>
 
         <ScrollViewer Grid.Row="1" HorizontalScrollBarVisibility="Disabled">
-          <ItemsControl Items="{Binding AppliedStyles}" >
+          <ItemsControl ItemsSource="{Binding AppliedStyles}" >
             <ItemsControl.ItemTemplate>
               <DataTemplate>
                 <Border BorderThickness="0,0,0,1" BorderBrush="#6C6C6C" Opacity="{Binding IsActive, Converter={StaticResource BoolToOpacity}}">
@@ -142,7 +142,7 @@
                       <TextBlock Grid.Row="0" Text="{Binding Name}" />
                     </Expander.Header>
 
-                    <ItemsControl Margin="20,0,0,0" Grid.Row="1" Items="{Binding Setters}">
+                    <ItemsControl Margin="20,0,0,0" Grid.Row="1" ItemsSource="{Binding Setters}">
                       
                       <ItemsControl.Styles>
                         <Style Selector="TextBlock.property-name">
@@ -253,7 +253,7 @@
         </ScrollViewer>
 
         <Expander Header="Pseudo Classes" Grid.Row="2">
-          <ItemsControl Items="{Binding PseudoClasses}">
+          <ItemsControl ItemsSource="{Binding PseudoClasses}">
             <ItemsControl.ItemsPanel>
               <ItemsPanelTemplate>
                 <WrapPanel />
diff --git a/src/Avalonia.Diagnostics/Diagnostics/Views/EventsPageView.xaml b/src/Avalonia.Diagnostics/Diagnostics/Views/EventsPageView.xaml
index fabd05077a..54c2f06709 100644
--- a/src/Avalonia.Diagnostics/Diagnostics/Views/EventsPageView.xaml
+++ b/src/Avalonia.Diagnostics/Diagnostics/Views/EventsPageView.xaml
@@ -45,7 +45,7 @@
                               UseWholeWordFilter="{Binding UseWholeWordFilter}"
                               UseRegexFilter="{Binding UseRegexFilter}" />
 
-      <TreeView Grid.Row="1" Items="{Binding Nodes}" SelectedItem="{Binding SelectedNode, Mode=TwoWay}" >
+      <TreeView Grid.Row="1" ItemsSource="{Binding Nodes}" SelectedItem="{Binding SelectedNode, Mode=TwoWay}" >
         <TreeView.DataTemplates>
           <TreeDataTemplate DataType="vm:EventTreeNodeBase"
                             ItemsSource="{Binding Children}">
@@ -71,7 +71,7 @@
 
     <Grid RowDefinitions="*,4,2*,Auto" Grid.Column="2">
 
-      <ListBox Name="EventsList" Items="{Binding RecordedEvents}"
+      <ListBox Name="EventsList" ItemsSource="{Binding RecordedEvents}"
                SelectedItem="{Binding SelectedEvent, Mode=TwoWay}">
 
         <ListBox.ItemTemplate>
@@ -108,7 +108,7 @@
       <DockPanel Grid.Row="2" LastChildFill="True">
         <TextBlock DockPanel.Dock="Top" FontSize="16" Text="Event chain:" />
 
-        <ListBox Items="{Binding SelectedEvent.EventChain}">
+        <ListBox ItemsSource="{Binding SelectedEvent.EventChain}">
           <ListBox.ItemTemplate>
             <DataTemplate>
               <ListBoxItem Classes.handled="{Binding Handled}">
diff --git a/src/Avalonia.Diagnostics/Diagnostics/Views/PropertyValueEditorView.cs b/src/Avalonia.Diagnostics/Diagnostics/Views/PropertyValueEditorView.cs
index 6e7729a350..6b52989f0b 100644
--- a/src/Avalonia.Diagnostics/Diagnostics/Views/PropertyValueEditorView.cs
+++ b/src/Avalonia.Diagnostics/Diagnostics/Views/PropertyValueEditorView.cs
@@ -221,7 +221,7 @@ namespace Avalonia.Diagnostics.Views
                 return CreateControl<ComboBox>(
                     SelectingItemsControl.SelectedItemProperty, init: c =>
                     {
-                        c.Items = Enum.GetValues(propertyType);
+                        c.ItemsSource = Enum.GetValues(propertyType);
                     });
 
             var tb = CreateControl<CommitTextBox>(
diff --git a/src/Avalonia.Diagnostics/Diagnostics/Views/TreePageView.xaml b/src/Avalonia.Diagnostics/Diagnostics/Views/TreePageView.xaml
index 3ca3d0b60e..9ffc301dc1 100644
--- a/src/Avalonia.Diagnostics/Diagnostics/Views/TreePageView.xaml
+++ b/src/Avalonia.Diagnostics/Diagnostics/Views/TreePageView.xaml
@@ -6,7 +6,7 @@
   <Grid ColumnDefinitions="0.35*,4,0.65*">
     <TreeView Name="tree"
               BorderThickness="0"
-              Items="{Binding Nodes}"
+              ItemsSource="{Binding Nodes}"
               SelectedItem="{Binding SelectedNode, Mode=TwoWay}">
       <TreeView.DataTemplates>
         <TreeDataTemplate DataType="vm:TreeNode"
diff --git a/src/Avalonia.FreeDesktop/Avalonia.FreeDesktop.csproj b/src/Avalonia.FreeDesktop/Avalonia.FreeDesktop.csproj
index 8791efd313..da9add1fa4 100644
--- a/src/Avalonia.FreeDesktop/Avalonia.FreeDesktop.csproj
+++ b/src/Avalonia.FreeDesktop/Avalonia.FreeDesktop.csproj
@@ -13,7 +13,7 @@
 
   <ItemGroup>
     <PackageReference Include="Tmds.DBus.Protocol" Version="0.14.0" />
-    <PackageReference Include="Tmds.DBus.SourceGenerator" Version="0.0.2" />
+    <PackageReference Include="Tmds.DBus.SourceGenerator" Version="0.0.4" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/src/Avalonia.FreeDesktop/DBusMenuExporter.cs b/src/Avalonia.FreeDesktop/DBusMenuExporter.cs
index d08828f796..3073ea580c 100644
--- a/src/Avalonia.FreeDesktop/DBusMenuExporter.cs
+++ b/src/Avalonia.FreeDesktop/DBusMenuExporter.cs
@@ -60,38 +60,42 @@ namespace Avalonia.FreeDesktop
 
             public override string Path { get; }
 
-            protected override (uint revision, (int, Dictionary<string, DBusVariantItem>, DBusVariantItem[]) layout) OnGetLayout(int parentId, int recursionDepth, string[] propertyNames)
+            protected override ValueTask<(uint revision, (int, Dictionary<string, DBusVariantItem>, DBusVariantItem[]) layout)> OnGetLayoutAsync(int parentId, int recursionDepth, string[] propertyNames)
             {
                 var menu = GetMenu(parentId);
                 var layout = GetLayout(menu.item, menu.menu, recursionDepth, propertyNames);
                 if (!IsNativeMenuExported)
                 {
                     IsNativeMenuExported = true;
-                    Dispatcher.UIThread.Post(() => OnIsNativeMenuExportedChanged?.Invoke(this, EventArgs.Empty));
+                    OnIsNativeMenuExportedChanged?.Invoke(this, EventArgs.Empty);
                 }
 
-                return (_revision, layout);
+                return new ValueTask<(uint, (int, Dictionary<string, DBusVariantItem>, DBusVariantItem[]))>((_revision, layout));
             }
 
-            protected override (int, Dictionary<string, DBusVariantItem>)[] OnGetGroupProperties(int[] ids, string[] propertyNames) =>
-                ids.Select(id => (id, GetProperties(GetMenu(id), propertyNames))).ToArray();
+            protected override ValueTask<(int, Dictionary<string, DBusVariantItem>)[]> OnGetGroupPropertiesAsync(int[] ids, string[] propertyNames)
+                => new(ids.Select(id => (id, GetProperties(GetMenu(id), propertyNames))).ToArray());
 
-            protected override DBusVariantItem OnGetProperty(int id, string name) => GetProperty(GetMenu(id), name) ?? new DBusVariantItem("i", new DBusInt32Item(0));
+            protected override ValueTask<DBusVariantItem> OnGetPropertyAsync(int id, string name) =>
+                new(GetProperty(GetMenu(id), name) ?? new DBusVariantItem("i", new DBusInt32Item(0)));
 
-            protected override void OnEvent(int id, string eventId, DBusVariantItem data, uint timestamp) =>
-                Dispatcher.UIThread.Post(() => HandleEvent(id, eventId));
+            protected override ValueTask OnEventAsync(int id, string eventId, DBusVariantItem data, uint timestamp)
+            {
+                HandleEvent(id, eventId);
+                return new ValueTask();
+            }
 
-            protected override int[] OnEventGroup((int, string, DBusVariantItem, uint)[] events)
+            protected override ValueTask<int[]> OnEventGroupAsync((int, string, DBusVariantItem, uint)[] events)
             {
                 foreach (var e in events)
-                    Dispatcher.UIThread.Post(() => HandleEvent(e.Item1, e.Item2));
-                return Array.Empty<int>();
+                    HandleEvent(e.Item1, e.Item2);
+                return new ValueTask<int[]>(Array.Empty<int>());
             }
 
-            protected override bool OnAboutToShow(int id) => false;
+            protected override ValueTask<bool> OnAboutToShowAsync(int id) => new(false);
 
-            protected override (int[] updatesNeeded, int[] idErrors) OnAboutToShowGroup(int[] ids) =>
-                (Array.Empty<int>(), Array.Empty<int>());
+            protected override ValueTask<(int[] updatesNeeded, int[] idErrors)> OnAboutToShowGroupAsync(int[] ids) =>
+                new((Array.Empty<int>(), Array.Empty<int>()));
 
             private async Task InitializeAsync()
             {
diff --git a/src/Avalonia.FreeDesktop/DBusTrayIconImpl.cs b/src/Avalonia.FreeDesktop/DBusTrayIconImpl.cs
index afbee77067..fed8b87bc9 100644
--- a/src/Avalonia.FreeDesktop/DBusTrayIconImpl.cs
+++ b/src/Avalonia.FreeDesktop/DBusTrayIconImpl.cs
@@ -1,8 +1,10 @@
 using System;
 using System.Diagnostics;
+using System.Threading.Tasks;
 using Avalonia.Controls.Platform;
 using Avalonia.Logging;
 using Avalonia.Platform;
+using Avalonia.Threading;
 using Tmds.DBus.Protocol;
 using Tmds.DBus.SourceGenerator;
 
@@ -219,13 +221,6 @@ namespace Avalonia.FreeDesktop
             Connection = connection;
             BackingProperties.Menu = dbusMenuPath;
             BackingProperties.ToolTip = (string.Empty, Array.Empty<(int, int, byte[])>(), string.Empty, string.Empty);
-            BackingProperties.IconName = string.Empty;
-            BackingProperties.AttentionIconName = string.Empty;
-            BackingProperties.AttentionIconPixmap = new []{ DBusTrayIconImpl.EmptyPixmap };
-            BackingProperties.AttentionMovieName = string.Empty;
-            BackingProperties.IconThemePath = string.Empty;
-            BackingProperties.OverlayIconName = string.Empty;
-            BackingProperties.OverlayIconPixmap = new []{ DBusTrayIconImpl.EmptyPixmap };
             InvalidateAll();
         }
 
@@ -235,13 +230,17 @@ namespace Avalonia.FreeDesktop
 
         public event Action? ActivationDelegate;
 
-        protected override void OnContextMenu(int x, int y) { }
+        protected override ValueTask OnContextMenuAsync(int x, int y) => new();
 
-        protected override void OnActivate(int x, int y) => ActivationDelegate?.Invoke();
+        protected override ValueTask OnActivateAsync(int x, int y)
+        {
+            Dispatcher.UIThread.Post(() => ActivationDelegate?.Invoke());
+            return new ValueTask();
+        }
 
-        protected override void OnSecondaryActivate(int x, int y) { }
+        protected override ValueTask OnSecondaryActivateAsync(int x, int y) => new();
 
-        protected override void OnScroll(int delta, string orientation) { }
+        protected override ValueTask OnScrollAsync(int delta, string orientation) => new();
 
         public void InvalidateAll()
         {
diff --git a/src/Avalonia.Themes.Fluent/Controls/DataValidationErrors.xaml b/src/Avalonia.Themes.Fluent/Controls/DataValidationErrors.xaml
index 7d45d0444f..984a523471 100644
--- a/src/Avalonia.Themes.Fluent/Controls/DataValidationErrors.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/DataValidationErrors.xaml
@@ -50,7 +50,7 @@
       <DataTemplate>
         <ItemsControl x:DataType="DataValidationErrors"
                       Foreground="{DynamicResource SystemControlErrorTextForegroundBrush}"
-                      Items="{Binding}">
+                      ItemsSource="{Binding}">
           <ItemsControl.Styles>
             <Style Selector="TextBlock">
               <Setter Property="TextWrapping" Value="Wrap" />
@@ -98,7 +98,7 @@
             </Style>
           </Panel.Styles>
           <ToolTip.Tip>
-            <ItemsControl Items="{Binding}" x:DataType="collections:IEnumerable" />
+            <ItemsControl ItemsSource="{Binding}" x:DataType="collections:IEnumerable" />
           </ToolTip.Tip>
           <Path Width="14"
                 Height="14"
diff --git a/src/Avalonia.Themes.Fluent/Controls/DatePicker.xaml b/src/Avalonia.Themes.Fluent/Controls/DatePicker.xaml
index 28ec553660..e71e733eff 100644
--- a/src/Avalonia.Themes.Fluent/Controls/DatePicker.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/DatePicker.xaml
@@ -127,7 +127,7 @@
 
             <Popup Name="PART_Popup" WindowManagerAddShadowHint="False"
                    IsLightDismissEnabled="True" PlacementTarget="{TemplateBinding}"
-                   PlacementMode="Bottom">
+                   Placement="Bottom">
               <DatePickerPresenter Name="PART_PickerPresenter" />
             </Popup>
 
diff --git a/src/Avalonia.Themes.Fluent/Controls/ManagedFileChooser.xaml b/src/Avalonia.Themes.Fluent/Controls/ManagedFileChooser.xaml
index d2581caaf5..b3453569a4 100644
--- a/src/Avalonia.Themes.Fluent/Controls/ManagedFileChooser.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/ManagedFileChooser.xaml
@@ -136,7 +136,7 @@
             x:DataType="internal:ManagedFileChooserViewModel">
       <ControlTemplate>
         <DockPanel>
-          <ListBox x:Name="PART_QuickLinks" DockPanel.Dock="Left" Items="{Binding QuickLinks}" SelectedIndex="{Binding QuickLinksSelectedIndex}" Focusable="False">
+          <ListBox x:Name="PART_QuickLinks" DockPanel.Dock="Left" ItemsSource="{Binding QuickLinks}" SelectedIndex="{Binding QuickLinksSelectedIndex}" Focusable="False">
             <ListBox.ItemTemplate>
               <DataTemplate>
                 <StackPanel Spacing="4" Orientation="Horizontal" Background="Transparent">
@@ -173,7 +173,7 @@
               <DockPanel DockPanel.Dock="Top" Margin="0,0,0,4">
                 <ComboBox DockPanel.Dock="Right"
                     IsVisible="{Binding ShowFilters}"
-                    Items="{Binding Filters}"
+                    ItemsSource="{Binding Filters}"
                     SelectedItem="{Binding SelectedFilter}" />
                 <TextBox Text="{Binding FileName}" Watermark="File name" IsVisible="{Binding !SelectingFolder}" />
               </DockPanel>
@@ -220,7 +220,7 @@
               <TextBlock Grid.Column="8" Text="Size" />
             </Grid>
             <ListBox x:Name="PART_Files"
-                Items="{Binding Items}"
+                ItemsSource="{Binding Items}"
                 Margin="0 5"
                 SelectionMode="{Binding SelectionMode}"
                 SelectedItems="{Binding SelectedItems}"
diff --git a/src/Avalonia.Themes.Fluent/Controls/Menu.xaml b/src/Avalonia.Themes.Fluent/Controls/Menu.xaml
index 692bac958a..c234cfd68e 100644
--- a/src/Avalonia.Themes.Fluent/Controls/Menu.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/Menu.xaml
@@ -37,6 +37,7 @@
                    MinWidth="{Binding Bounds.Width, RelativeSource={RelativeSource TemplatedParent}}"
                    IsLightDismissEnabled="True"
                    IsOpen="{TemplateBinding IsSubMenuOpen, Mode=TwoWay}"
+                   Placement="BottomEdgeAlignedLeft"
                    OverlayInputPassThroughElement="{Binding $parent[Menu]}">
               <Border Background="{DynamicResource MenuFlyoutPresenterBackground}"
                       BorderBrush="{DynamicResource MenuFlyoutPresenterBorderBrush}"
diff --git a/src/Avalonia.Themes.Fluent/Controls/MenuItem.xaml b/src/Avalonia.Themes.Fluent/Controls/MenuItem.xaml
index 72a7797bc3..5a10c62860 100644
--- a/src/Avalonia.Themes.Fluent/Controls/MenuItem.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/MenuItem.xaml
@@ -118,7 +118,7 @@
           </Border>
           <Popup Name="PART_Popup"
                  WindowManagerAddShadowHint="False"
-                 PlacementMode="Right"
+                 Placement="Right"
                  HorizontalOffset="{DynamicResource MenuFlyoutSubItemPopupHorizontalOffset}"
                  IsLightDismissEnabled="False"
                  IsOpen="{TemplateBinding IsSubMenuOpen, Mode=TwoWay}">
diff --git a/src/Avalonia.Themes.Fluent/Controls/NativeMenuBar.xaml b/src/Avalonia.Themes.Fluent/Controls/NativeMenuBar.xaml
index d5c95ab46c..515a5a730b 100644
--- a/src/Avalonia.Themes.Fluent/Controls/NativeMenuBar.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/NativeMenuBar.xaml
@@ -7,13 +7,13 @@
       <ControlTemplate>
         <Menu
           IsVisible="{Binding !$parent[TopLevel].(NativeMenu.IsNativeMenuExported)}"
-          Items="{Binding $parent[TopLevel].(NativeMenu.Menu).Items}">
+          ItemsSource="{Binding $parent[TopLevel].(NativeMenu.Menu).Items}">
           <Menu.Styles>
             <Style Selector="MenuItem" x:DataType="NativeMenuItem">
               <Setter Property="Header" Value="{Binding Header}"/>
               <Setter Property="IsEnabled" Value="{Binding IsEnabled}"/>
               <Setter Property="InputGesture" Value="{Binding Gesture}"/>
-              <Setter Property="Items" Value="{Binding Menu.Items}"/>
+              <Setter Property="ItemsSource" Value="{Binding Menu.Items}"/>
               <Setter Property="Command" Value="{Binding Command}"/>
               <Setter Property="CommandParameter" Value="{Binding CommandParameter}"/>
               <Setter Property="(NativeMenuBar.EnableMenuItemClickForwarding)" Value="True"/>
diff --git a/src/Avalonia.Themes.Fluent/Controls/TimePicker.xaml b/src/Avalonia.Themes.Fluent/Controls/TimePicker.xaml
index 71ff0eaebc..39f7b0b224 100644
--- a/src/Avalonia.Themes.Fluent/Controls/TimePicker.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/TimePicker.xaml
@@ -151,7 +151,7 @@
                    WindowManagerAddShadowHint="False"
                    IsLightDismissEnabled="True"
                    PlacementTarget="{TemplateBinding}"
-                   PlacementMode="Bottom">
+                   Placement="Bottom">
               <TimePickerPresenter Name="PART_PickerPresenter" />
             </Popup>
 
diff --git a/src/Avalonia.Themes.Simple/Controls/DataValidationErrors.xaml b/src/Avalonia.Themes.Simple/Controls/DataValidationErrors.xaml
index ef8c6625bd..a4e5ab2d90 100644
--- a/src/Avalonia.Themes.Simple/Controls/DataValidationErrors.xaml
+++ b/src/Avalonia.Themes.Simple/Controls/DataValidationErrors.xaml
@@ -35,7 +35,7 @@
           </Canvas.Styles>
           <ToolTip.Tip>
             <ItemsControl x:DataType="DataValidationErrors"
-                          Items="{Binding}" />
+                          ItemsSource="{Binding}" />
           </ToolTip.Tip>
           <Path Data="M14,7 A7,7 0 0,0 0,7 M0,7 A7,7 0 1,0 14,7 M7,3l0,5 M7,9l0,2"
                 Stroke="{DynamicResource ErrorBrush}"
diff --git a/src/Avalonia.Themes.Simple/Controls/DatePicker.xaml b/src/Avalonia.Themes.Simple/Controls/DatePicker.xaml
index 5c57240aea..6cf352518a 100644
--- a/src/Avalonia.Themes.Simple/Controls/DatePicker.xaml
+++ b/src/Avalonia.Themes.Simple/Controls/DatePicker.xaml
@@ -142,7 +142,7 @@
 
             <Popup Name="PART_Popup"
                    IsLightDismissEnabled="True"
-                   PlacementMode="Bottom"
+                   Placement="Bottom"
                    PlacementTarget="{TemplateBinding}"
                    WindowManagerAddShadowHint="False">
               <DatePickerPresenter Name="PART_PickerPresenter" />
diff --git a/src/Avalonia.Themes.Simple/Controls/ManagedFileChooser.xaml b/src/Avalonia.Themes.Simple/Controls/ManagedFileChooser.xaml
index 2ef112f51c..a5b0649655 100644
--- a/src/Avalonia.Themes.Simple/Controls/ManagedFileChooser.xaml
+++ b/src/Avalonia.Themes.Simple/Controls/ManagedFileChooser.xaml
@@ -101,7 +101,7 @@
           <ComboBox Margin="0,5,0,0"
                     DockPanel.Dock="Bottom"
                     IsVisible="{Binding ShowFilters}"
-                    Items="{Binding Filters}"
+                    ItemsSource="{Binding Filters}"
                     SelectedItem="{Binding SelectedFilter}" />
 
           <TextBox DockPanel.Dock="Bottom"
@@ -114,7 +114,7 @@
                    BorderBrush="Transparent"
                    DockPanel.Dock="Left"
                    Focusable="False"
-                   Items="{Binding QuickLinks}"
+                   ItemsSource="{Binding QuickLinks}"
                    SelectedIndex="{Binding QuickLinksSelectedIndex}">
             <ListBox.ItemTemplate>
               <DataTemplate>
@@ -160,7 +160,7 @@
             </Grid>
             <ListBox x:Name="PART_Files"
                      Margin="0,5"
-                     Items="{Binding Items}"
+                     ItemsSource="{Binding Items}"
                      ScrollViewer.HorizontalScrollBarVisibility="Disabled"
                      SelectedItems="{Binding SelectedItems}"
                      SelectionMode="{Binding SelectionMode}">
diff --git a/src/Avalonia.Themes.Simple/Controls/Menu.xaml b/src/Avalonia.Themes.Simple/Controls/Menu.xaml
index 797aeedd23..0b3064412d 100644
--- a/src/Avalonia.Themes.Simple/Controls/Menu.xaml
+++ b/src/Avalonia.Themes.Simple/Controls/Menu.xaml
@@ -26,8 +26,8 @@
             </ContentPresenter>
             <Popup Name="PART_Popup"
                    IsLightDismissEnabled="True"
-                   IsOpen="{TemplateBinding IsSubMenuOpen,
-                                            Mode=TwoWay}"
+                   IsOpen="{TemplateBinding IsSubMenuOpen, Mode=TwoWay}"
+                   Placement="BottomEdgeAlignedLeft"
                    OverlayInputPassThroughElement="{Binding $parent[Menu]}">
               <Border Background="{DynamicResource ThemeBackgroundBrush}"
                       BorderBrush="{DynamicResource ThemeBorderMidBrush}"
diff --git a/src/Avalonia.Themes.Simple/Controls/MenuItem.xaml b/src/Avalonia.Themes.Simple/Controls/MenuItem.xaml
index 6056938938..7ec666eaf9 100644
--- a/src/Avalonia.Themes.Simple/Controls/MenuItem.xaml
+++ b/src/Avalonia.Themes.Simple/Controls/MenuItem.xaml
@@ -65,7 +65,7 @@
                    IsLightDismissEnabled="False"
                    IsOpen="{TemplateBinding IsSubMenuOpen,
                                             Mode=TwoWay}"
-                   PlacementMode="Right">
+                   Placement="Right">
               <Border Background="{DynamicResource ThemeBackgroundBrush}"
                       BorderBrush="{DynamicResource ThemeBorderMidBrush}"
                       BorderThickness="{TemplateBinding BorderThickness}">
diff --git a/src/Avalonia.Themes.Simple/Controls/NativeMenuBar.xaml b/src/Avalonia.Themes.Simple/Controls/NativeMenuBar.xaml
index 945622f22f..625bf71e66 100644
--- a/src/Avalonia.Themes.Simple/Controls/NativeMenuBar.xaml
+++ b/src/Avalonia.Themes.Simple/Controls/NativeMenuBar.xaml
@@ -7,13 +7,13 @@
     <Setter Property="Template">
       <ControlTemplate>
         <Menu IsVisible="{Binding !$parent[TopLevel].(NativeMenu.IsNativeMenuExported)}"
-              Items="{Binding $parent[TopLevel].(NativeMenu.Menu).Items}">
+              ItemsSource="{Binding $parent[TopLevel].(NativeMenu.Menu).Items}">
           <Menu.Styles>
             <Style Selector="MenuItem" x:DataType="NativeMenuItem">
               <Setter Property="Header" Value="{Binding Header}"/>
               <Setter Property="IsEnabled" Value="{Binding IsEnabled}"/>
               <Setter Property="InputGesture" Value="{Binding Gesture}"/>
-              <Setter Property="Items" Value="{Binding Menu.Items}"/>
+              <Setter Property="ItemsSource" Value="{Binding Menu.Items}"/>
               <Setter Property="Command" Value="{Binding Command}"/>
               <Setter Property="CommandParameter" Value="{Binding CommandParameter}"/>
               <Setter Property="(NativeMenuBar.EnableMenuItemClickForwarding)" Value="True"/>
diff --git a/src/Avalonia.Themes.Simple/Controls/TimePicker.xaml b/src/Avalonia.Themes.Simple/Controls/TimePicker.xaml
index 58066bb9a5..5acbc41a68 100644
--- a/src/Avalonia.Themes.Simple/Controls/TimePicker.xaml
+++ b/src/Avalonia.Themes.Simple/Controls/TimePicker.xaml
@@ -156,7 +156,7 @@
 
             <Popup Name="PART_Popup"
                    IsLightDismissEnabled="True"
-                   PlacementMode="Bottom"
+                   Placement="Bottom"
                    PlacementTarget="{TemplateBinding}"
                    WindowManagerAddShadowHint="False">
               <TimePickerPresenter Name="PART_PickerPresenter" />
diff --git a/src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/Transformers/AvaloniaXamlIlDataContextTypeTransformer.cs b/src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/Transformers/AvaloniaXamlIlDataContextTypeTransformer.cs
index a24d4eb6e9..681d2a38d4 100644
--- a/src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/Transformers/AvaloniaXamlIlDataContextTypeTransformer.cs
+++ b/src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/Transformers/AvaloniaXamlIlDataContextTypeTransformer.cs
@@ -73,27 +73,32 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
                     // Infer data type from collection binding on a control that displays items.
                     var property = context.ParentNodes().OfType<XamlPropertyAssignmentNode>().FirstOrDefault();
                     var attributeType = context.GetAvaloniaTypes().InheritDataTypeFromItemsAttribute;
-                    var attribute = property?.Property?.GetClrProperty().CustomAttributes
-                        .FirstOrDefault(a => a.Type == attributeType);
-    
-                    if (attribute is not null)
+                    var attributes = property?.Property?.GetClrProperty().CustomAttributes
+                        .Where(a => a.Type == attributeType).ToList();
+
+                    if (attributes?.Count > 0)
                     {
-                        var propertyName = (string)attribute.Parameters.First();
-                        XamlAstConstructableObjectNode parentObject;
-                        if (attribute.Properties.TryGetValue("AncestorType", out var type)
-                            && type is IXamlType xamlType)
-                        {
-                            parentObject = context.ParentNodes().OfType<XamlAstConstructableObjectNode>()
-                                .FirstOrDefault(n => n.Type.GetClrType().FullName == xamlType.FullName);
-                        }
-                        else
+                        foreach (var attribute in attributes)
                         {
-                            parentObject = context.ParentNodes().OfType<XamlAstConstructableObjectNode>().FirstOrDefault();
-                        }
-                            
-                        if (parentObject != null)
-                        {
-                            inferredDataContextTypeNode = InferDataContextOfPresentedItem(context, on, parentObject, propertyName);
+                            var propertyName = (string)attribute.Parameters.First();
+                            XamlAstConstructableObjectNode parentObject;
+                            if (attribute.Properties.TryGetValue("AncestorType", out var type)
+                                && type is IXamlType xamlType)
+                            {
+                                parentObject = context.ParentNodes().OfType<XamlAstConstructableObjectNode>()
+                                    .FirstOrDefault(n => n.Type.GetClrType().FullName == xamlType.FullName);
+                            }
+                            else
+                            {
+                                parentObject = context.ParentNodes().OfType<XamlAstConstructableObjectNode>().FirstOrDefault();
+                            }
+
+                            if (parentObject != null)
+                            {
+                                inferredDataContextTypeNode = InferDataContextOfPresentedItem(context, on, parentObject, propertyName);
+                                if (inferredDataContextTypeNode != null)
+                                    break;
+                            }
                         }
                     }
                     
diff --git a/src/Skia/Avalonia.Skia/DrawingContextImpl.cs b/src/Skia/Avalonia.Skia/DrawingContextImpl.cs
index e3e2f664c3..671e4d134c 100644
--- a/src/Skia/Avalonia.Skia/DrawingContextImpl.cs
+++ b/src/Skia/Avalonia.Skia/DrawingContextImpl.cs
@@ -375,7 +375,7 @@ namespace Avalonia.Skia
 
             foreach (var boxShadow in boxShadows)
             {
-                if (!boxShadow.IsDefault && !boxShadow.IsInset)
+                if (boxShadow != default && !boxShadow.IsInset)
                 {
                     using (var shadow = BoxShadowFilter.Create(_boxShadowPaint, boxShadow, _useOpacitySaveLayer ? 1 : _currentOpacity))
                     {
@@ -432,7 +432,7 @@ namespace Avalonia.Skia
 
             foreach (var boxShadow in boxShadows)
             {
-                if (!boxShadow.IsDefault && boxShadow.IsInset)
+                if (boxShadow != default && boxShadow.IsInset)
                 {
                     using (var shadow = BoxShadowFilter.Create(_boxShadowPaint, boxShadow, _useOpacitySaveLayer ? 1 : _currentOpacity))
                     {
diff --git a/src/Windows/Avalonia.Win32/TrayIconImpl.cs b/src/Windows/Avalonia.Win32/TrayIconImpl.cs
index c19439c09e..05d9faa97b 100644
--- a/src/Windows/Avalonia.Win32/TrayIconImpl.cs
+++ b/src/Windows/Avalonia.Win32/TrayIconImpl.cs
@@ -150,7 +150,7 @@ namespace Avalonia.Win32
                 TransparencyLevelHint = WindowTransparencyLevel.Transparent,
                 Content = new TrayIconMenuFlyoutPresenter()
                 {
-                    Items = menuItems
+                    ItemsSource = menuItems
                 }
             };
 
diff --git a/src/Windows/Avalonia.Win32/Win32NativeToManagedMenuExporter.cs b/src/Windows/Avalonia.Win32/Win32NativeToManagedMenuExporter.cs
index 46cdf66653..ab4ec00b75 100644
--- a/src/Windows/Avalonia.Win32/Win32NativeToManagedMenuExporter.cs
+++ b/src/Windows/Avalonia.Win32/Win32NativeToManagedMenuExporter.cs
@@ -39,7 +39,7 @@ namespace Avalonia.Win32
 
                     if (item.Menu != null)
                     {
-                        newItem.Items = Populate(item.Menu);
+                        newItem.ItemsSource = Populate(item.Menu);
                     }
                     else if (item.HasClickHandlers && item is INativeMenuItemExporterEventsImplBridge bridge)
                     {
diff --git a/tests/Avalonia.Base.UnitTests/Styling/SetterTests.cs b/tests/Avalonia.Base.UnitTests/Styling/SetterTests.cs
index 33023c4851..009a26ba18 100644
--- a/tests/Avalonia.Base.UnitTests/Styling/SetterTests.cs
+++ b/tests/Avalonia.Base.UnitTests/Styling/SetterTests.cs
@@ -72,51 +72,51 @@ namespace Avalonia.Base.UnitTests.Styling
         [Fact]
         public void Can_Set_Direct_Property_In_Style_Without_Activator()
         {
-            var control = new TextBlock();
+            var control = new DirectPropertyClass();
             var target = new Setter();
-            var style = new Style(x => x.Is<TextBlock>())
+            var style = new Style(x => x.Is<DirectPropertyClass>())
             {
                 Setters =
                 {
-                    new Setter(TextBlock.TextProperty, "foo"),
+                    new Setter(DirectPropertyClass.FooProperty, "foo"),
                 }
             };
 
             Apply(style, control);
 
-            Assert.Equal("foo", control.Text);
+            Assert.Equal("foo", control.Foo);
         }
 
         [Fact]
         public void Can_Set_Direct_Property_Binding_In_Style_Without_Activator()
         {
-            var control = new TextBlock();
+            var control = new DirectPropertyClass();
             var target = new Setter();
             var source = new BehaviorSubject<object?>("foo");
-            var style = new Style(x => x.Is<TextBlock>())
+            var style = new Style(x => x.Is<DirectPropertyClass>())
             {
                 Setters =
                 {
-                    new Setter(TextBlock.TextProperty, source.ToBinding()),
+                    new Setter(DirectPropertyClass.FooProperty, source.ToBinding()),
                 }
             };
 
             Apply(style, control);
 
-            Assert.Equal("foo", control.Text);
+            Assert.Equal("foo", control.Foo);
         }
 
         [Fact]
         public void Cannot_Set_Direct_Property_Binding_In_Style_With_Activator()
         {
-            var control = new TextBlock();
+            var control = new DirectPropertyClass();
             var target = new Setter();
             var source = new BehaviorSubject<object?>("foo");
-            var style = new Style(x => x.Is<TextBlock>().Class("foo"))
+            var style = new Style(x => x.Is<DirectPropertyClass>().Class("foo"))
             {
                 Setters =
                 {
-                    new Setter(TextBlock.TextProperty, source.ToBinding()),
+                    new Setter(DirectPropertyClass.FooProperty, source.ToBinding()),
                 }
             };
 
@@ -126,13 +126,13 @@ namespace Avalonia.Base.UnitTests.Styling
         [Fact]
         public void Cannot_Set_Direct_Property_In_Style_With_Activator()
         {
-            var control = new TextBlock();
+            var control = new DirectPropertyClass();
             var target = new Setter();
-            var style = new Style(x => x.Is<TextBlock>().Class("foo"))
+            var style = new Style(x => x.Is<DirectPropertyClass>().Class("foo"))
             {
                 Setters =
                 {
-                    new Setter(TextBlock.TextProperty, "foo"),
+                    new Setter(DirectPropertyClass.FooProperty, "foo"),
                 }
             };
 
@@ -288,18 +288,18 @@ namespace Avalonia.Base.UnitTests.Styling
         {
             using var app = UnitTestApplication.Start(TestServices.MockThreadingInterface);
             var data = new Data { Foo = "foo" };
-            var control = new TextBox
+            var control = new DirectPropertyClass
             {
                 DataContext = data,
             };
 
-            var style = new Style(x => x.OfType<TextBox>())
+            var style = new Style(x => x.OfType<DirectPropertyClass>())
             {
                 Setters =
                 {
                     new Setter
                     {
-                        Property = TextBox.TextProperty,
+                        Property = DirectPropertyClass.FooProperty,
                         Value = new Binding
                         {
                             Path = "Foo",
@@ -310,9 +310,9 @@ namespace Avalonia.Base.UnitTests.Styling
             };
 
             Apply(style, control);
-            Assert.Equal("foo", control.Text);
+            Assert.Equal("foo", control.Foo);
 
-            control.Text = "bar";
+            control.Foo = "bar";
             Assert.Equal("bar", data.Foo);
         }
 
@@ -502,9 +502,9 @@ namespace Avalonia.Base.UnitTests.Styling
             Assert.Equal(Brushes.Blue, data.Bar);
         }
 
-        private void Apply(Style style, Control control)
+        private void Apply(Style style, StyledElement element)
         {
-            StyleHelpers.TryAttach(style, control);
+            StyleHelpers.TryAttach(style, element);
         }
 
         private void Apply(Setter setter, Control control)
@@ -535,5 +535,18 @@ namespace Avalonia.Base.UnitTests.Styling
                 throw new NotImplementedException();
             }
         }
+
+        private class DirectPropertyClass : StyledElement
+        {
+            public static readonly DirectProperty<DirectPropertyClass, string?> FooProperty = AvaloniaProperty.RegisterDirect<DirectPropertyClass, string?>(nameof(Foo),
+                x => x.Foo, (x, v) => x.Foo = v);
+            
+            private string? _foo;
+            public string? Foo
+            {
+                get => _foo;
+                set => SetAndRaise(FooProperty, ref _foo, value);
+            }
+        }
     }
 }
diff --git a/tests/Avalonia.Controls.UnitTests/CarouselTests.cs b/tests/Avalonia.Controls.UnitTests/CarouselTests.cs
index 2b043e0e48..c6237c2fa8 100644
--- a/tests/Avalonia.Controls.UnitTests/CarouselTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/CarouselTests.cs
@@ -23,7 +23,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new Carousel
             {
                 Template = CarouselTemplate(),
-                Items = new[]
+                ItemsSource = new[]
                 {
                     "Foo",
                     "Bar"
@@ -43,7 +43,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new Carousel
             {
                 Template = CarouselTemplate(),
-                Items = new[]
+                ItemsSource = new[]
                 {
                     "Foo",
                     "Bar"
@@ -73,7 +73,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new Carousel
             {
                 Template = CarouselTemplate(),
-                Items = items,
+                ItemsSource = items,
             };
 
             Prepare(target);
@@ -88,7 +88,7 @@ namespace Avalonia.Controls.UnitTests
             newItems.RemoveAt(0);
             Layout(target);
 
-            target.Items = newItems;
+            target.ItemsSource = newItems;
             Layout(target);
 
             child = GetContainerTextBlock(target.GetRealizedContainers().Single());
@@ -104,7 +104,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new Carousel
             {
                 Template = CarouselTemplate(),
-                Items = items,
+                ItemsSource = items,
             };
 
             Prepare(target);
@@ -133,7 +133,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new Carousel
             {
                 Template = CarouselTemplate(),
-                Items = items,
+                ItemsSource = items,
             };
 
             Prepare(target);
@@ -144,7 +144,7 @@ namespace Avalonia.Controls.UnitTests
 
             Assert.Equal("Foo", child.Text);
 
-            target.Items = null;
+            target.ItemsSource = null;
             Layout(target);
 
             var numChildren = target.GetRealizedContainers().Count();
@@ -166,7 +166,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new Carousel
             {
                 Template = CarouselTemplate(),
-                Items = items,
+                ItemsSource = items,
                 SelectedIndex = 2
             };
 
@@ -193,7 +193,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new Carousel
             {
                 Template = CarouselTemplate(),
-                Items = items,
+                ItemsSource = items,
             };
 
             Prepare(target);
@@ -225,7 +225,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new Carousel
             {
                 Template = CarouselTemplate(),
-                Items = items,
+                ItemsSource = items,
             };
 
             Prepare(target);
diff --git a/tests/Avalonia.Controls.UnitTests/ComboBoxTests.cs b/tests/Avalonia.Controls.UnitTests/ComboBoxTests.cs
index e206d809d3..9523d5db7f 100644
--- a/tests/Avalonia.Controls.UnitTests/ComboBoxTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/ComboBoxTests.cs
@@ -23,7 +23,7 @@ namespace Avalonia.Controls.UnitTests
         {
             var target = new ComboBox
             {
-                Items = new[] { "Foo", "Bar" },
+                ItemsSource = new[] { "Foo", "Bar" },
             };
 
             _helper.Down(target);
@@ -43,7 +43,7 @@ namespace Avalonia.Controls.UnitTests
         {
             var target = new ComboBox
             {
-                Items = new[] { "Foo", "Bar" },
+                ItemsSource = new[] { "Foo", "Bar" },
             };
 
             _helper.Down(target);
@@ -66,15 +66,14 @@ namespace Avalonia.Controls.UnitTests
         {
             using (UnitTestApplication.Start(TestServices.RealFocus))
             {
-                var items = new[]
-                {
-                    new ComboBoxItem() { Content = "bla" },
-                    new ComboBoxItem() { Content = "dd" },
-                    new ComboBoxItem() { Content = "sdf", IsEnabled = false }
-                };
                 var target = new ComboBox
                 {
-                    Items = items,
+                    Items =
+                    {
+                        new ComboBoxItem() { Content = "bla" },
+                        new ComboBoxItem() { Content = "dd" },
+                        new ComboBoxItem() { Content = "sdf", IsEnabled = false }
+                    },
                     Template = GetTemplate(),
                     WrapSelection = true
                 };
@@ -104,15 +103,14 @@ namespace Avalonia.Controls.UnitTests
         {
             using (UnitTestApplication.Start(TestServices.RealFocus))
             {
-                var items = new[]
-                {
-                    new ComboBoxItem() { Content = "bla" },
-                    new ComboBoxItem() { Content = "dd", IsEnabled = false },
-                    new ComboBoxItem() { Content = "sdf" }
-                };
                 var target = new ComboBox
                 {
-                    Items = items,
+                    Items =
+                    {
+                        new ComboBoxItem() { Content = "bla" },
+                        new ComboBoxItem() { Content = "dd", IsEnabled = false },
+                        new ComboBoxItem() { Content = "sdf" }
+                    },
                     Template = GetTemplate()
                 };
                 var root = new TestRoot(target);
@@ -139,10 +137,9 @@ namespace Avalonia.Controls.UnitTests
         [Fact]
         public void SelectionBoxItem_Is_Rectangle_With_VisualBrush_When_Selection_Is_Control()
         {
-            var items = new[] { new Canvas() };
             var target = new ComboBox
             {
-                Items = items,
+                Items = { new Canvas() },
                 SelectedIndex = 0,
             };
             var root = new TestRoot(target);
@@ -152,7 +149,7 @@ namespace Avalonia.Controls.UnitTests
 
             var brush = rectangle.Fill as VisualBrush;
             Assert.NotNull(brush);
-            Assert.Same(items[0], brush.Visual);
+            Assert.Same(target.Items[0], brush.Visual);
         }
 
         [Fact]
@@ -160,7 +157,7 @@ namespace Avalonia.Controls.UnitTests
         {
             var target = new ComboBox
             {
-                Items = new[] { new Canvas() },
+                Items = { new Canvas() },
                 SelectedIndex = 0,
                 Template = GetTemplate(),
             };
@@ -218,7 +215,7 @@ namespace Avalonia.Controls.UnitTests
             {
                 var target = new ComboBox
                 {
-                    Items = new[] { new Canvas() },
+                    Items = { new Canvas() },
                     SelectedIndex = 0,
                     Template = GetTemplate(),
                 };
@@ -257,7 +254,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ComboBox
                 {
                     Template = GetTemplate(),                    
-                    Items = items.Select(x => new ComboBoxItem { Content = x })
+                    ItemsSource = items.Select(x => new ComboBoxItem { Content = x })
                 };
 
                 target.ApplyTemplate();
@@ -326,7 +323,7 @@ namespace Avalonia.Controls.UnitTests
 
                 var target = new ComboBox
                 {
-                    Items = new[] { new Canvas() },
+                    Items = { new Canvas() },
                     SelectedIndex = 0,
                     Template = GetTemplate(),
                 };
@@ -363,17 +360,16 @@ namespace Avalonia.Controls.UnitTests
         [Fact]
         public void FlowDirection_Of_RectangleContent_Shuold_Be_LeftToRight()
         {
-            var items = new[]
-            {
-                new ComboBoxItem()
-                { 
-                    Content = new Control()
-                }
-            };
             var target = new ComboBox
             {
                 FlowDirection = FlowDirection.RightToLeft,
-                Items = items,
+                Items =
+                {
+                    new ComboBoxItem()
+                    {
+                        Content = new Control()
+                    }
+                },
                 Template = GetTemplate()
             };
 
@@ -393,16 +389,15 @@ namespace Avalonia.Controls.UnitTests
             {
                 Child = new Control()
             };
-            var items = new[]
-            { 
-                new ComboBoxItem()
-                {
-                    Content = parentContent.Child
-                }
-            };
             var target = new ComboBox
             {
-                Items = items,
+                Items = 
+                {
+                    new ComboBoxItem()
+                    {
+                        Content = parentContent.Child
+                    }
+                },
                 Template = GetTemplate()
             };
 
@@ -428,17 +423,16 @@ namespace Avalonia.Controls.UnitTests
                 {
                     Child = new Control()
                 };
-                var items = new[]
-                { 
-                    new ComboBoxItem()
-                    {
-                        Content = parentContent.Child
-                    }
-                };
                 var target = new ComboBox
                 {
                     FlowDirection = FlowDirection.RightToLeft,
-                    Items = items,
+                    Items =
+                    {
+                        new ComboBoxItem()
+                        {
+                            Content = parentContent.Child
+                        }
+                    },
                     Template = GetTemplate()
                 };
 
diff --git a/tests/Avalonia.Controls.UnitTests/ContextMenuTests.cs b/tests/Avalonia.Controls.UnitTests/ContextMenuTests.cs
index d99c90cb77..803cc793fd 100644
--- a/tests/Avalonia.Controls.UnitTests/ContextMenuTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/ContextMenuTests.cs
@@ -303,7 +303,7 @@ namespace Avalonia.Controls.UnitTests
                 window.Show();
 
                 var c = new ContextMenu();
-                c.PlacementMode = PlacementMode.Bottom;
+                c.Placement = PlacementMode.Bottom;
                 c.Open(button);
 
                 var overlay = LightDismissOverlayLayer.GetLightDismissOverlayLayer(window);
diff --git a/tests/Avalonia.Controls.UnitTests/ItemsControlTests.cs b/tests/Avalonia.Controls.UnitTests/ItemsControlTests.cs
index 7b5aa83b46..41aaa7b670 100644
--- a/tests/Avalonia.Controls.UnitTests/ItemsControlTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/ItemsControlTests.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Collections.Specialized;
 using System.Linq;
@@ -16,6 +17,46 @@ namespace Avalonia.Controls.UnitTests
 {
     public class ItemsControlTests
     {
+        [Fact]
+        public void Setting_ItemsSource_Should_Populate_Items()
+        {
+            var target = new ItemsControl
+            {
+                Template = GetTemplate(),
+                ItemTemplate = new FuncDataTemplate<string>((_, __) => new Canvas()),
+                ItemsSource = new[] { "foo", "bar" },
+            };
+
+            Assert.NotSame(target.ItemsSource, target.Items);
+            Assert.Equal(target.ItemsSource, target.Items);
+        }
+
+        [Fact]
+        public void Cannot_Set_ItemsSource_With_Items_Present()
+        {
+            var target = new ItemsControl
+            {
+                Template = GetTemplate(),
+                ItemTemplate = new FuncDataTemplate<string>((_, __) => new Canvas()),
+                Items = { "foo", "bar" },
+            };
+
+            Assert.Throws<InvalidOperationException>(() => target.ItemsSource = new[] { "baz" });
+        }
+
+        [Fact]
+        public void Cannot_Modify_Items_When_ItemsSource_Set()
+        {
+            var target = new ItemsControl
+            {
+                Template = GetTemplate(),
+                ItemTemplate = new FuncDataTemplate<string>((_, __) => new Canvas()),
+                ItemsSource = Array.Empty<string>(),
+            };
+
+            Assert.Throws<InvalidOperationException>(() => target.Items.Add("foo"));
+        }
+
         [Fact]
         public void Should_Use_ItemTemplate_To_Create_Control()
         {
@@ -25,7 +66,7 @@ namespace Avalonia.Controls.UnitTests
                 ItemTemplate = new FuncDataTemplate<string>((_, __) => new Canvas()),
             };
 
-            target.Items = new[] { "Foo" };
+            target.ItemsSource = new[] { "Foo" };
             target.ApplyTemplate();
             target.Presenter.ApplyTemplate();
 
@@ -44,7 +85,7 @@ namespace Avalonia.Controls.UnitTests
                 ItemTemplate = new FuncDataTemplate<string>((_, __) => new Canvas()),
             };
 
-            target.Items = new[] { "Foo" };
+            target.ItemsSource = new[] { "Foo" };
             target.ApplyTemplate();
             target.Presenter.ApplyTemplate();
 
@@ -66,7 +107,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ItemsControl();
 
             target.Template = GetTemplate();
-            target.Items = new[] { "Foo" };
+            target.ItemsSource = new[] { "Foo" };
             target.ApplyTemplate();
             target.Presenter.ApplyTemplate();
 
@@ -79,7 +120,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ItemsControl();
 
             target.Template = GetTemplate();
-            target.Items = new[] { "Foo" };
+            target.ItemsSource = new[] { "Foo" };
             target.ApplyTemplate();
             target.Presenter!.ApplyTemplate();
 
@@ -92,7 +133,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ItemsControl();
 
             target.Template = GetTemplate();
-            target.Items = new[] { "Foo" };
+            target.ItemsSource = new[] { "Foo" };
             target.ApplyTemplate();
             target.Presenter.ApplyTemplate();
 
@@ -111,7 +152,7 @@ namespace Avalonia.Controls.UnitTests
             };
 
             target.Template = GetTemplate();
-            target.Items = new[] { "Foo" };
+            target.ItemsSource = new[] { "Foo" };
             target.ApplyTemplate();
             target.Presenter.ApplyTemplate();
 
@@ -134,7 +175,7 @@ namespace Avalonia.Controls.UnitTests
                 target.TemplatedParent = templatedParent;
                 target.Template = GetTemplate();
 
-                target.Items = new[] { "Foo" };
+                target.ItemsSource = new[] { "Foo" };
 
                 root.ApplyTemplate();
                 target.ApplyTemplate();
@@ -153,7 +194,7 @@ namespace Avalonia.Controls.UnitTests
             var child = new Control();
 
             target.Template = GetTemplate();
-            target.Items = new[] { child };
+            target.Items.Add(child);
 
             Assert.Equal(child.Parent, target);
             Assert.Equal(child.GetLogicalParent(), target);
@@ -171,7 +212,7 @@ namespace Avalonia.Controls.UnitTests
             var child = new Control();
 
             target.Template = GetTemplate();
-            target.Items = new[] { child };
+            target.Items.Add(child);
             root.LayoutManager.ExecuteInitialLayoutPass();
 
             Assert.Equal(target, child.Parent);
@@ -188,7 +229,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ItemsControl
             {
                 Template = GetTemplate(),
-                Items = items,
+                ItemsSource = items,
             };
 
             var root = new TestRoot(true, target);
@@ -206,11 +247,13 @@ namespace Avalonia.Controls.UnitTests
         {
             var target = new ItemsControl();
             var child = new Control();
-            var items = new AvaloniaList<Control>(child);
 
             target.Template = GetTemplate();
-            target.Items = items;
-            items.RemoveAt(0);
+            target.Items.Add(child);
+
+            Assert.Single(target.GetLogicalChildren());
+
+            target.Items.RemoveAt(0);
 
             Assert.Null(child.Parent);
             Assert.Null(child.GetLogicalParent());
@@ -224,151 +267,127 @@ namespace Avalonia.Controls.UnitTests
             var child = new Control();
 
             target.Template = GetTemplate();
-            target.Items = new[] { child };
-            target.Items = null;
-
-            Assert.Null(child.Parent);
-            Assert.Null(((ILogical)child).LogicalParent);
-        }
+            target.Items.Add(child);
 
-        [Fact]
-        public void Clearing_Items_Should_Clear_Child_Controls_Parent()
-        {
-            var target = new ItemsControl();
-            var child = new Control();
+            Assert.Single(target.GetLogicalChildren());
 
-            target.Template = GetTemplate();
-            target.Items = new[] { child };
-            target.ApplyTemplate();
-            target.Items = null;
+            target.Items.Clear();
 
             Assert.Null(child.Parent);
             Assert.Null(((ILogical)child).LogicalParent);
         }
 
         [Fact]
-        public void Adding_Control_Item_Should_Make_Control_Appear_In_LogicalChildren()
+        public void Assigning_ItemsSource_Should_Not_Fire_LogicalChildren_CollectionChanged_Before_ApplyTemplate()
         {
             var target = new ItemsControl();
             var child = new Control();
+            var called = false;
 
-            target.Template = GetTemplate();
-            target.Items = new[] { child };
-
-            // Should appear both before and after applying template.
-            Assert.Equal(new ILogical[] { child }, target.GetLogicalChildren());
+            ((ILogical)target).LogicalChildren.CollectionChanged += (s, e) => called = true;
 
-            target.ApplyTemplate();
+            var list = new AvaloniaList<Control>(new[] { child });
+            target.ItemsSource = list;
 
-            Assert.Equal(new ILogical[] { child }, target.GetLogicalChildren());
+            Assert.False(called);
         }
 
         [Fact]
-        public void Adding_String_Item_Should_Make_ContentPresenter_Appear_In_LogicalChildren()
+        public void Changing_ItemsSource_Should_Not_Fire_LogicalChildren_CollectionChanged_Before_ApplyTemplate()
         {
             var target = new ItemsControl();
             var child = new Control();
+            var called = false;
 
-            target.Template = GetTemplate();
-            target.Items = new[] { "Foo" };
-            target.ApplyTemplate();
-            target.Presenter.ApplyTemplate();
+            ((ILogical)target).LogicalChildren.CollectionChanged += (s, e) => called = true;
 
-            var logical = (ILogical)target;
-            Assert.Equal(1, logical.LogicalChildren.Count);
-            Assert.IsType<ContentPresenter>(logical.LogicalChildren[0]);
+            var list = new AvaloniaList<Control>();
+            target.ItemsSource = list;
+            list.Add(child);
+
+            Assert.False(called);
         }
 
         [Fact]
-        public void Setting_Items_To_Null_Should_Remove_LogicalChildren()
+        public void Clearing_Items_Should_Clear_Child_Controls_Parent()
         {
             var target = new ItemsControl();
             var child = new Control();
 
             target.Template = GetTemplate();
-            target.Items = new[] { "Foo" };
+            target.Items.Add(child);
             target.ApplyTemplate();
-            target.Presenter.ApplyTemplate();
-
-            Assert.NotEmpty(target.GetLogicalChildren());
-
-            target.Items = null;
+            target.Items.Clear();
 
-            Assert.Equal(new ILogical[0], target.GetLogicalChildren());
+            Assert.Null(child.Parent);
+            Assert.Null(((ILogical)child).LogicalParent);
         }
 
-
         [Fact]
-        public void Setting_Items_Should_Fire_LogicalChildren_CollectionChanged()
+        public void Adding_Control_Item_Should_Make_Control_Appear_In_LogicalChildren()
         {
             var target = new ItemsControl();
             var child = new Control();
-            var called = false;
 
             target.Template = GetTemplate();
-            target.ApplyTemplate();
+            target.Items.Add(child);
 
-            ((ILogical)target).LogicalChildren.CollectionChanged += (s, e) =>
-                called = e.Action == NotifyCollectionChangedAction.Add;
+            // Should appear both before and after applying template.
+            Assert.Equal(new ILogical[] { child }, target.GetLogicalChildren());
 
-            target.Items = new[] { child };
+            target.ApplyTemplate();
 
-            Assert.True(called);
+            Assert.Equal(new ILogical[] { child }, target.GetLogicalChildren());
         }
 
         [Fact]
-        public void Setting_Items_To_Null_Should_Fire_LogicalChildren_CollectionChanged()
+        public void Adding_String_Item_Should_Make_ContentPresenter_Appear_In_LogicalChildren()
         {
             var target = new ItemsControl();
-            var child = new Control();
-            var called = false;
 
             target.Template = GetTemplate();
-            target.Items = new[] { child };
+            target.ItemsSource = new[] { "Foo" };
             target.ApplyTemplate();
+            target.Presenter.ApplyTemplate();
 
-            ((ILogical)target).LogicalChildren.CollectionChanged += (s, e) =>
-                called = e.Action == NotifyCollectionChangedAction.Remove;
-
-            target.Items = null;
-
-            Assert.True(called);
+            var logical = (ILogical)target;
+            Assert.Equal(1, logical.LogicalChildren.Count);
+            Assert.IsType<ContentPresenter>(logical.LogicalChildren[0]);
         }
 
         [Fact]
-        public void Changing_Items_Should_Fire_LogicalChildren_CollectionChanged()
+        public void Adding_Items_Should_Fire_LogicalChildren_CollectionChanged()
         {
             var target = new ItemsControl();
             var child = new Control();
             var called = false;
 
             target.Template = GetTemplate();
-            target.Items = new[] { child };
             target.ApplyTemplate();
 
-            ((ILogical)target).LogicalChildren.CollectionChanged += (s, e) => called = true;
+            ((ILogical)target).LogicalChildren.CollectionChanged += (s, e) =>
+                called = e.Action == NotifyCollectionChangedAction.Add;
 
-            target.Items = new[] { "Foo" };
+            target.Items.Add(child);
 
             Assert.True(called);
         }
 
         [Fact]
-        public void Adding_Items_Should_Fire_LogicalChildren_CollectionChanged()
+        public void Clearing_Items_Should_Fire_LogicalChildren_CollectionChanged()
         {
             var target = new ItemsControl();
-            var items = new AvaloniaList<string> { "Foo" };
+            var child = new Control();
             var called = false;
 
             target.Template = GetTemplate();
-            target.Items = items;
+            target.Items.Add(child);
             target.ApplyTemplate();
-            target.Presenter.ApplyTemplate();
 
             ((ILogical)target).LogicalChildren.CollectionChanged += (s, e) =>
-                called = e.Action == NotifyCollectionChangedAction.Add;
+                called = e.Action == NotifyCollectionChangedAction.Remove;
 
-            items.Add("Bar");
+            target.Items.Clear();
 
             Assert.True(called);
         }
@@ -381,16 +400,13 @@ namespace Avalonia.Controls.UnitTests
             var called = false;
 
             target.Template = GetTemplate();
-            target.Items = items;
-            target.ApplyTemplate();
-            target.Presenter.ApplyTemplate();
+            target.ItemsSource = items;
 
-            ((ILogical)target).LogicalChildren.CollectionChanged += (s, e) =>
-                called = e.Action == NotifyCollectionChangedAction.Remove;
+            ((ILogical)target).LogicalChildren.CollectionChanged += (s, e) => called = true;
 
             items.Remove("Bar");
 
-            Assert.True(called);
+            Assert.False(called);
         }
 
         [Fact]
@@ -418,7 +434,7 @@ namespace Avalonia.Controls.UnitTests
         {
             var target = new ItemsControl
             {
-                Items = new[] { "foo", "bar" },
+                ItemsSource = new[] { "foo", "bar" },
                 Template = GetTemplate(),
             };
 
@@ -451,7 +467,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ItemsControl()
             {
                 Template = GetTemplate(),
-                Items = new[] { 1, 2, 3 },
+                ItemsSource = new[] { 1, 2, 3 },
             };
 
             Assert.DoesNotContain(":empty", target.Classes);
@@ -474,10 +490,10 @@ namespace Avalonia.Controls.UnitTests
             var target = new ItemsControl()
             {
                 Template = GetTemplate(),
-                Items = new[] { 1, 2, 3 },
+                ItemsSource = new[] { 1, 2, 3 },
             };
 
-            target.Items = new int[0];
+            target.ItemsSource = new int[0];
 
             Assert.Contains(":empty", target.Classes);
         }
@@ -488,7 +504,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ItemsControl()
             {
                 Template = GetTemplate(),
-                Items = new[] { 1, 2, 3 },
+                ItemsSource = new[] { 1, 2, 3 },
             };
 
             Assert.Equal(3, target.ItemCount);
@@ -502,7 +518,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ItemsControl()
             {
                 Template = GetTemplate(),
-                Items = items,
+                ItemsSource = items,
             };
 
             items.Add(4);
@@ -522,7 +538,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ItemsControl()
             {
                 Template = GetTemplate(),
-                Items = items,
+                ItemsSource = items,
             };
 
             items.Clear();
@@ -538,7 +554,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ItemsControl()
             {
                 Template = GetTemplate(),
-                Items = items,
+                ItemsSource = items,
             };
 
             items.Add(1);
@@ -547,14 +563,14 @@ namespace Avalonia.Controls.UnitTests
         }
 
         [Fact]
-        public void Single_Item_Class_Should_Be_Set_When_Items_Collection_Count_Increases_To_One()
+        public void Single_Item_Class_Should_Be_Set_When_ItemsSource_Collection_Count_Increases_To_One()
         {
             var items = new ObservableCollection<int>() { };
 
             var target = new ItemsControl()
             {
                 Template = GetTemplate(),
-                Items = items,
+                ItemsSource = items,
             };
 
             items.Add(1);
@@ -570,7 +586,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ItemsControl()
             {
                 Template = GetTemplate(),
-                Items = items,
+                ItemsSource = items,
             };
 
             items.Clear();
@@ -586,7 +602,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ItemsControl()
             {
                 Template = GetTemplate(),
-                Items = items,
+                ItemsSource = items,
             };
 
             items.Add(2);
@@ -613,7 +629,7 @@ namespace Avalonia.Controls.UnitTests
                 {
                     new FuncDataTemplate<Item>((x, __) => new Button { Content = x })
                 },
-                Items = items,
+                ItemsSource = items,
             };
 
             target.ApplyTemplate();
@@ -641,7 +657,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ItemsControl
             {
                 Template = GetTemplate(),
-                Items = items,
+                ItemsSource = items,
             };
 
             target.ApplyTemplate();
@@ -665,7 +681,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ItemsControl
                 {
                     Template = GetTemplate(),
-                    Items = items,
+                    ItemsSource = items,
                 };
 
                 var root = new TestRoot { Child = target };
@@ -701,7 +717,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ItemsControl
                 {
                     Template = GetTemplate(),
-                    Items = items,
+                    ItemsSource = items,
                 };
 
                 var root = new TestRoot { Child = target };
@@ -729,7 +745,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ItemsControl
             {
                 Template = GetTemplate(),
-                Items = new[] { "foo", "bar" },
+                ItemsSource = new[] { "foo", "bar" },
                 ItemTemplate = new FuncDataTemplate<string>((_, __) => new Canvas()),
             };
 
@@ -755,7 +771,7 @@ namespace Avalonia.Controls.UnitTests
                 DisplayMemberBinding = new Binding("Length")
             };
 
-            target.Items = new[] { "Foo" };
+            target.ItemsSource = new[] { "Foo" };
             target.ApplyTemplate();
             target.Presenter.ApplyTemplate();
 
@@ -774,7 +790,7 @@ namespace Avalonia.Controls.UnitTests
                 DisplayMemberBinding = new Binding("Value")
             };
 
-            target.Items = new[] { new Item("Foo", "Bar") };
+            target.ItemsSource = new[] { new Item("Foo", "Bar") };
             target.ApplyTemplate();
             target.Presenter.ApplyTemplate();
 
@@ -816,6 +832,135 @@ namespace Avalonia.Controls.UnitTests
             Assert.Throws<InvalidOperationException>(() => target.DisplayMemberBinding = new Binding("Length"));
         }
 
+        [Fact]
+        public void ContainerPrepared_Is_Raised_For_Each_Item_Container_On_Layout()
+        {
+            var target = new ItemsControl
+            {
+                Template = GetTemplate(),
+                Items = { "Foo", "Bar", "Baz" },
+            };
+
+            var result = new List<Control>();
+            var index = 0;
+
+            target.ContainerPrepared += (s, e) =>
+            {
+                Assert.Equal(index++, e.Index);
+                result.Add(e.Container);
+            };
+
+            target.ApplyTemplate();
+            target.Presenter.ApplyTemplate();
+
+            Assert.Equal(3, result.Count);
+            Assert.Equal(target.GetRealizedContainers(), result);
+        }
+
+        [Fact]
+        public void ContainerPrepared_Is_Raised_For_Each_ItemsSource_Container_On_Layout()
+        {
+            var target = new ItemsControl
+            {
+                Template = GetTemplate(),
+                ItemsSource = new[] { "Foo", "Bar", "Baz" },
+            };
+
+            var result = new List<Control>();
+            var index = 0;
+
+            target.ContainerPrepared += (s, e) =>
+            {
+                Assert.Equal(index++, e.Index);
+                result.Add(e.Container);
+            };
+
+            target.ApplyTemplate();
+            target.Presenter.ApplyTemplate();
+
+            Assert.Equal(3, result.Count);
+            Assert.Equal(target.GetRealizedContainers(), result);
+        }
+
+        [Fact]
+        public void ContainerPrepared_Is_Raised_For_Added_Item()
+        {
+            var target = new ItemsControl
+            {
+                Template = GetTemplate(),
+                Items = { "Foo", "Bar", "Baz" },
+            };
+
+            target.ApplyTemplate();
+            target.Presenter.ApplyTemplate();
+
+            var result = new List<Control>();
+
+            target.ContainerPrepared += (s, e) =>
+            {
+                Assert.Equal(3, e.Index);
+                result.Add(e.Container);
+            };
+
+            target.Items.Add("Qux");
+
+            Assert.Equal(1, result.Count);
+        }
+
+        [Fact]
+        public void ContainerIndexChanged_Is_Raised_When_Item_Added()
+        {
+            var target = new ItemsControl
+            {
+                Template = GetTemplate(),
+                Items = { "Foo", "Bar", "Baz" },
+            };
+
+            target.ApplyTemplate();
+            target.Presenter.ApplyTemplate();
+
+            var result = new List<Control>();
+            var index = 1;
+
+            target.ContainerIndexChanged += (s, e) =>
+            {
+                Assert.Equal(index++, e.OldIndex);
+                Assert.Equal(index, e.NewIndex);
+                result.Add(e.Container);
+            };
+
+            target.Items.Insert(1, "Qux");
+
+            Assert.Equal(2, result.Count);
+            Assert.Equal(target.GetRealizedContainers().Skip(2), result);
+        }
+
+        [Fact]
+        public void ContainerClearing_Is_Raised_When_Item_Removed()
+        {
+            var target = new ItemsControl
+            {
+                Template = GetTemplate(),
+                Items = { "Foo", "Bar", "Baz" },
+            };
+
+            target.ApplyTemplate();
+            target.Presenter.ApplyTemplate();
+
+            var expected = target.ContainerFromIndex(1);
+            var raised = 0;
+
+            target.ContainerClearing += (s, e) =>
+            {
+                Assert.Same(expected, e.Container);
+                ++raised;
+            };
+
+            target.Items.RemoveAt(1);
+
+            Assert.Equal(1, raised);
+        }
+
         private class Item
         {
             public Item(string value)
diff --git a/tests/Avalonia.Controls.UnitTests/ItemsSourceViewTests.cs b/tests/Avalonia.Controls.UnitTests/ItemsSourceViewTests.cs
index df842b21a7..faa143bb8e 100644
--- a/tests/Avalonia.Controls.UnitTests/ItemsSourceViewTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/ItemsSourceViewTests.cs
@@ -38,6 +38,35 @@ namespace Avalonia.Controls.UnitTests
             Assert.Throws<ArgumentException>(() => ItemsSourceView.GetOrCreate(source));
         }
 
+        [Fact]
+        public void Reassigning_Source_Unsubscribes_From_Previous_Source()
+        {
+            var source = new AvaloniaList<string>();
+            var target = new ReassignableItemsSourceView(source);
+            var debug = (INotifyCollectionChangedDebug)source;
+
+            target.CollectionChanged += (s, e) => { };
+
+            Assert.Equal(1, debug.GetCollectionChangedSubscribers().Length);
+
+            target.SetSource(new string[0]);
+
+            Assert.Null(debug.GetCollectionChangedSubscribers());
+        }
+
+        [Fact]
+        public void Reassigning_Source_Subscribes_To_New_Source()
+        {
+            var source = new AvaloniaList<string>();
+            var target = new ReassignableItemsSourceView(new string[0]);
+            var debug = (INotifyCollectionChangedDebug)source;
+
+            target.CollectionChanged += (s, e) => { };
+            target.SetSource(source);
+
+            Assert.Equal(1, debug.GetCollectionChangedSubscribers().Length);
+        }
+
         private class InvalidCollection : INotifyCollectionChanged, IEnumerable<string>
         {
             public event NotifyCollectionChangedEventHandler CollectionChanged { add { } remove { } }
@@ -52,5 +81,15 @@ namespace Avalonia.Controls.UnitTests
                 yield break;
             }
         }
+
+        private class ReassignableItemsSourceView : ItemsSourceView
+        {
+            public ReassignableItemsSourceView(IEnumerable source)
+                : base(source)
+            {
+            }
+
+            public new void SetSource(IEnumerable source) => base.SetSource(source);
+        }
     }
 }
diff --git a/tests/Avalonia.Controls.UnitTests/ListBoxTests.cs b/tests/Avalonia.Controls.UnitTests/ListBoxTests.cs
index 8170545f68..f42185a59c 100644
--- a/tests/Avalonia.Controls.UnitTests/ListBoxTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/ListBoxTests.cs
@@ -29,7 +29,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ListBox
             {
                 Template = ListBoxTemplate(),
-                Items = new[] { "Foo" },
+                ItemsSource = new[] { "Foo" },
                 ItemTemplate = new FuncDataTemplate<string>((_, __) => new Canvas()),
             };
 
@@ -81,7 +81,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ListBox
                 {
                     Template = ListBoxTemplate(),
-                    Items = items,
+                    ItemsSource = items,
                 };
 
                 Prepare(target);
@@ -107,7 +107,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ListBox
                 {
                     Template = ListBoxTemplate(),
-                    Items = items,
+                    ItemsSource = items,
                     ItemContainerTheme = theme,
                 };
 
@@ -124,12 +124,11 @@ namespace Avalonia.Controls.UnitTests
         {
             using (UnitTestApplication.Start(TestServices.MockPlatformRenderInterface))
             {
-                var items = new[] { "Foo", "Bar", "Baz " };
                 var theme = new ControlTheme(typeof(ListBoxItem));
                 var target = new ListBox
                 {
                     Template = ListBoxTemplate(),
-                    Items = new[] { new ListBoxItem() },
+                    Items = { new ListBoxItem() },
                     ItemContainerTheme = theme,
                 };
 
@@ -149,7 +148,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ListBox
                 {
                     Template = ListBoxTemplate(),
-                    Items = new[] { "Foo", "Bar", "Baz " },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz " },
                 };
 
                 Prepare(target);
@@ -184,7 +183,7 @@ namespace Avalonia.Controls.UnitTests
                     {
                         new FuncDataTemplate<Item>((x, _) => new Button { Content = x })
                     },
-                    Items = items,
+                    ItemsSource = items,
                 };
 
                 Prepare(target);
@@ -208,7 +207,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ListBox
                 {
                     Template = ListBoxTemplate(),
-                    Items = Enumerable.Range(0, 20).Select(x => $"Item {x}").ToList(),
+                    ItemsSource = Enumerable.Range(0, 20).Select(x => $"Item {x}").ToList(),
                     ItemTemplate = new FuncDataTemplate<string>((x, _) => new TextBlock { Height = 10 }),
                     SelectedIndex = 0,
                 };
@@ -236,7 +235,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ListBox
                 {
                     Template = ListBoxTemplate(),
-                    Items = Enumerable.Range(0, 20).Select(x => $"Item {x}").ToList(),
+                    ItemsSource = Enumerable.Range(0, 20).Select(x => $"Item {x}").ToList(),
                     ItemTemplate = new FuncDataTemplate<string>((x, _) => new TextBlock { Width = 20, Height = 10 }),
                     SelectedIndex = 0,
                 };
@@ -258,7 +257,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ListBox
                 {
                     Template = ListBoxTemplate(),
-                    Items = items,
+                    ItemsSource = items,
                     ItemTemplate = new FuncDataTemplate<string>((x, _) => new TextBlock { Width = 20, Height = 10 }),
                     SelectedIndex = 0,
                 };
@@ -272,7 +271,7 @@ namespace Avalonia.Controls.UnitTests
                 items.Remove("Item 2");
                 Layout(target);
 
-                var actual = target.Presenter.Panel.Children.Cast<ListBoxItem>().Select(x => (string)x.Content).ToList();
+                var actual = target.GetRealizedContainers().Cast<ListBoxItem>().Select(x => (string)x.Content).ToList();
                 Assert.Equal(items.OrderBy(x => x), actual.OrderBy(x => x));
             }
         }
@@ -286,7 +285,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ListBox
                 {
                     Template = ListBoxTemplate(),
-                    Items = items,
+                    ItemsSource = items,
                     SelectionMode = SelectionMode.Toggle,
                     ItemTemplate = new FuncDataTemplate<string>((x, _) => new TextBlock { Height = 10 })
                 };
@@ -318,7 +317,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ListBox
                 {
                     Template = ListBoxTemplate(),
-                    Items = items,
+                    ItemsSource = items,
                     ItemTemplate = new FuncDataTemplate<string>((x, _) => new TextBlock { Height = 10 })
                 };
 
@@ -364,7 +363,7 @@ namespace Avalonia.Controls.UnitTests
 
                 lm.ExecuteInitialLayoutPass();
 
-                target.Items = items;
+                target.ItemsSource = items;
 
                 lm.ExecuteLayoutPass();
 
@@ -415,7 +414,7 @@ namespace Avalonia.Controls.UnitTests
                     Height = 100,
                     Width = 50,
                     ItemTemplate = new FuncDataTemplate<object>((c, _) => new Border() { Height = 10 }),
-                    Items = items,
+                    ItemsSource = items,
                 };
                 wnd.Content = target;
 
@@ -450,7 +449,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ListBox
                 {
                     Template = ListBoxTemplate(),
-                    Items = items,
+                    ItemsSource = items,
                     ItemTemplate = new FuncDataTemplate<string>((x, _) => new TextBlock { Height = 10 }),
                     SelectionMode = SelectionMode.AlwaysSelected,
                 };
@@ -497,7 +496,7 @@ namespace Avalonia.Controls.UnitTests
                     AutoScrollToSelectedItem = true,
                     Width = 50,
                     ItemTemplate = new FuncDataTemplate<object>((c, _) => new Border() { Height = 10 }),
-                    Items = items,
+                    ItemsSource = items,
                 };
                 wnd.Content = target;
 
@@ -533,7 +532,7 @@ namespace Avalonia.Controls.UnitTests
         {
             var target = new ListBox
             {
-                [!ListBox.ItemsProperty] = new Binding("Items"),
+                [!ListBox.ItemsSourceProperty] = new Binding("Items"),
                 [!ListBox.SelectedItemsProperty] = new Binding("SelectedItems"),
             };
 
@@ -650,7 +649,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ListBox
             {
                 Template = ListBoxTemplate(),
-                Items = new[] { "Foo" },
+                ItemsSource = new[] { "Foo" },
                 ItemTemplate = new FuncDataTemplate<string>((_, __) => new Canvas()),
                 SelectionMode = SelectionMode.AlwaysSelected,
             };
@@ -672,7 +671,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ListBox
             {
                 Template = ListBoxTemplate(),
-                Items = items,
+                ItemsSource = items,
                 ItemTemplate = new FuncDataTemplate<string>((_, __) => new Canvas { Height = 10 }),
             };
 
@@ -703,7 +702,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ListBox
             {
                 Template = ListBoxTemplate(),
-                Items = items,
+                ItemsSource = items,
                 ItemTemplate = new FuncDataTemplate<string>((_, __) => new Canvas { Height = 10 }),
                 AutoScrollToSelectedItem = true,
                 SelectedIndex = 1,
@@ -749,7 +748,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ListBox
                 {
                     Template = ListBoxTemplate(),
-                    Items = items,
+                    ItemsSource = items,
                     ItemTemplate = new FuncDataTemplate<string>((x, _) => new TextBlock { Height = 10 }),
                     WrapSelection = true
                 };
@@ -786,6 +785,146 @@ namespace Avalonia.Controls.UnitTests
             }
         }
 
+        [Fact]
+        public void ContainerPrepared_Is_Raised_For_Each_Item_Container_On_Layout()
+        {
+            using var app = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface);
+
+            var target = new ListBox
+            {
+                Template = ListBoxTemplate(),
+                Items = { "Foo", "Bar", "Baz" },
+            };
+
+            var result = new List<Control>();
+            var index = 0;
+
+            target.ContainerPrepared += (s, e) =>
+            {
+                Assert.Equal(index++, e.Index);
+                result.Add(e.Container);
+            };
+
+            Prepare(target);
+
+            Assert.Equal(3, result.Count);
+            Assert.Equal(target.GetRealizedContainers(), result);
+        }
+
+        [Fact]
+        public void ContainerPrepared_Is_Raised_For_Each_ItemsSource_Container_On_Layout()
+        {
+            using var app = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface);
+
+            var target = new ListBox
+            {
+                Template = ListBoxTemplate(),
+                ItemsSource = new[] { "Foo", "Bar", "Baz" },
+            };
+
+            var result = new List<Control>();
+            var index = 0;
+
+            target.ContainerPrepared += (s, e) =>
+            {
+                Assert.Equal(index++, e.Index);
+                result.Add(e.Container);
+            };
+
+            Prepare(target);
+
+            Assert.Equal(3, result.Count);
+            Assert.Equal(target.GetRealizedContainers(), result);
+        }
+
+        [Fact]
+        public void ContainerPrepared_Is_Raised_For_Added_Item()
+        {
+            using var app = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface);
+
+            var data = new AvaloniaList<string> { "Foo", "Bar", "Baz" };
+            var target = new ListBox
+            {
+                Template = ListBoxTemplate(),
+                ItemsSource = data,
+            };
+
+            Prepare(target);
+
+            var result = new List<Control>();
+
+            target.ContainerPrepared += (s, e) =>
+            {
+                Assert.Equal(3, e.Index);
+                result.Add(e.Container);
+            };
+
+            data.Add("Qux");
+            Layout(target);
+
+            Assert.Equal(1, result.Count);
+        }
+
+        [Fact]
+        public void ContainerIndexChanged_Is_Raised_When_Item_Added()
+        {
+            using var app = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface);
+
+            var data = new AvaloniaList<string> { "Foo", "Bar", "Baz" };
+            var target = new ListBox
+            {
+                Template = ListBoxTemplate(),
+                ItemsSource = data,
+            };
+
+            Prepare(target);
+
+            var result = new List<Control>();
+            var index = 1;
+
+            target.ContainerIndexChanged += (s, e) =>
+            {
+                Assert.Equal(index++, e.OldIndex);
+                Assert.Equal(index, e.NewIndex);
+                result.Add(e.Container);
+            };
+
+            data.Insert(1, "Qux");
+            Layout(target);
+
+            Assert.Equal(2, result.Count);
+            Assert.Equal(target.GetRealizedContainers().Skip(2), result);
+        }
+
+        [Fact]
+        public void ContainerClearing_Is_Raised_When_Item_Removed()
+        {
+            using var app = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface);
+
+            var data = new AvaloniaList<string> { "Foo", "Bar", "Baz" };
+            var target = new ListBox
+            {
+                Template = ListBoxTemplate(),
+                ItemsSource = data,
+            };
+
+            Prepare(target);
+
+            var expected = target.ContainerFromIndex(1);
+            var raised = 0;
+
+            target.ContainerClearing += (s, e) =>
+            {
+                Assert.Same(expected, e.Container);
+                ++raised;
+            };
+
+            data.RemoveAt(1);
+            Layout(target);
+
+            Assert.Equal(1, raised);
+        }
+
         private class ResettingCollection : List<string>, INotifyCollectionChanged
         {
             public ResettingCollection(int itemCount)
diff --git a/tests/Avalonia.Controls.UnitTests/ListBoxTests_Multiple.cs b/tests/Avalonia.Controls.UnitTests/ListBoxTests_Multiple.cs
index 942eb8bf5b..7a724b070e 100644
--- a/tests/Avalonia.Controls.UnitTests/ListBoxTests_Multiple.cs
+++ b/tests/Avalonia.Controls.UnitTests/ListBoxTests_Multiple.cs
@@ -18,7 +18,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ListBox
             {
                 Template = new FuncControlTemplate(CreateListBoxTemplate),
-                Items = new[] { "Foo", "Bar", "Baz " },
+                ItemsSource = new[] { "Foo", "Bar", "Baz " },
                 SelectionMode = SelectionMode.Multiple
             };
 
@@ -41,7 +41,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ListBox
             {
                 Template = new FuncControlTemplate(CreateListBoxTemplate),
-                Items = new[] { "Foo", "Bar", "Baz " },
+                ItemsSource = new[] { "Foo", "Bar", "Baz " },
                 SelectionMode = SelectionMode.Multiple
             };
 
@@ -64,7 +64,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ListBox
             {
                 Template = new FuncControlTemplate(CreateListBoxTemplate),
-                Items = new[] { "Foo", "Bar", "Baz " },
+                ItemsSource = new[] { "Foo", "Bar", "Baz " },
                 SelectionMode = SelectionMode.Multiple
             };
 
diff --git a/tests/Avalonia.Controls.UnitTests/ListBoxTests_Single.cs b/tests/Avalonia.Controls.UnitTests/ListBoxTests_Single.cs
index 131642fc4e..5551d1c7df 100644
--- a/tests/Avalonia.Controls.UnitTests/ListBoxTests_Single.cs
+++ b/tests/Avalonia.Controls.UnitTests/ListBoxTests_Single.cs
@@ -26,7 +26,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ListBox
             {
                 Template = new FuncControlTemplate(CreateListBoxTemplate),
-                Items = new[] { "Foo", "Bar", "Baz " },
+                ItemsSource = new[] { "Foo", "Bar", "Baz " },
             };
 
             ApplyTemplate(target);
@@ -45,7 +45,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ListBox
             {
                 Template = new FuncControlTemplate(CreateListBoxTemplate),
-                Items = new[] { "Foo", "Bar", "Baz " },
+                ItemsSource = new[] { "Foo", "Bar", "Baz " },
             };
 
             ApplyTemplate(target);
@@ -64,7 +64,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ListBox
             {
                 Template = new FuncControlTemplate(CreateListBoxTemplate),
-                Items = new[] { "Foo", "Bar", "Baz " },
+                ItemsSource = new[] { "Foo", "Bar", "Baz " },
             };
 
             ApplyTemplate(target);
@@ -86,7 +86,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ListBox
                 {
                     Template = new FuncControlTemplate(CreateListBoxTemplate),
-                    Items = new[] { "Foo", "Bar", "Baz " },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz " },
                 };
                 AvaloniaLocator.CurrentMutable.Bind<PlatformHotkeyConfiguration>().ToConstant(new Mock<PlatformHotkeyConfiguration>().Object);
                 ApplyTemplate(target);
@@ -116,7 +116,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ListBox
                 {
                     Template = new FuncControlTemplate(CreateListBoxTemplate),
-                    Items = new[] { "Foo", "Bar", "Baz " },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz " },
                 };
                 AvaloniaLocator.CurrentMutable.Bind<PlatformHotkeyConfiguration>().ToConstant(new Mock<PlatformHotkeyConfiguration>().Object);
                 ApplyTemplate(target);
@@ -134,7 +134,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ListBox
                 {
                     Template = new FuncControlTemplate(CreateListBoxTemplate),
-                    Items = new[] { "Foo", "Bar", "Baz " },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz " },
                 };
                 AvaloniaLocator.CurrentMutable.Bind<PlatformHotkeyConfiguration>().ToConstant(new Mock<PlatformHotkeyConfiguration>().Object);
                 ApplyTemplate(target);
@@ -154,7 +154,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ListBox
                 {
                     Template = new FuncControlTemplate(CreateListBoxTemplate),
-                    Items = new[] { "Foo", "Bar", "Baz " },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz " },
                     SelectionMode = SelectionMode.Single | SelectionMode.Toggle,
                 };
                 AvaloniaLocator.CurrentMutable.Bind<PlatformHotkeyConfiguration>().ToConstant(new Mock<PlatformHotkeyConfiguration>().Object);
@@ -174,7 +174,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ListBox
                 {
                     Template = new FuncControlTemplate(CreateListBoxTemplate),
-                    Items = new[] { "Foo", "Bar", "Baz " },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz " },
                     SelectionMode = SelectionMode.Toggle,
                 };
 
@@ -196,7 +196,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ListBox
                 {
                     Template = new FuncControlTemplate(CreateListBoxTemplate),
-                    Items = new[] { "Foo", "Bar", "Baz " },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz " },
                     SelectionMode = SelectionMode.Toggle | SelectionMode.AlwaysSelected,
                 };
                 AvaloniaLocator.CurrentMutable.Bind<PlatformHotkeyConfiguration>().ToConstant(new Mock<PlatformHotkeyConfiguration>().Object);
@@ -217,7 +217,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new ListBox
                 {
                     Template = new FuncControlTemplate(CreateListBoxTemplate),
-                    Items = new[] { "Foo", "Bar", "Baz " },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz " },
                     SelectionMode = SelectionMode.Single | SelectionMode.Toggle,
                 };
                 AvaloniaLocator.CurrentMutable.Bind<PlatformHotkeyConfiguration>().ToConstant(new Mock<PlatformHotkeyConfiguration>().Object);
@@ -236,7 +236,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new ListBox
             {
                 Template = new FuncControlTemplate(CreateListBoxTemplate),
-                Items = new[] { "Foo", "Bar", "Baz " },
+                ItemsSource = new[] { "Foo", "Bar", "Baz " },
             };
 
             ApplyTemplate(target);
@@ -259,7 +259,7 @@ namespace Avalonia.Controls.UnitTests
             {
                 Template = new FuncControlTemplate(CreateListBoxTemplate),
                 DataContext = viewModel,
-                Items = viewModel.Items
+                ItemsSource = viewModel.Items
             };
 
             target.Bind(ListBox.SelectedItemProperty,
diff --git a/tests/Avalonia.Controls.UnitTests/MenuItemTests.cs b/tests/Avalonia.Controls.UnitTests/MenuItemTests.cs
index e80ca17993..1049ff2678 100644
--- a/tests/Avalonia.Controls.UnitTests/MenuItemTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/MenuItemTests.cs
@@ -191,7 +191,7 @@ namespace Avalonia.Controls.UnitTests
                     return true;
                 });
                 var target = new MenuItem();
-                var contextMenu = new ContextMenu { Items = new AvaloniaList<MenuItem> { target } };
+                var contextMenu = new ContextMenu { Items = { target } };
                 var window = new Window { Content = new Panel { ContextMenu = contextMenu } };
                 window.ApplyStyling();
                 window.ApplyTemplate();
@@ -270,8 +270,8 @@ namespace Avalonia.Controls.UnitTests
                     return true;
                 });
                 var target = new MenuItem();
-                var parentMenuItem = new MenuItem { Items = new AvaloniaList<MenuItem> { target } };
-                var contextMenu = new ContextMenu { Items = new AvaloniaList<MenuItem> { parentMenuItem } };
+                var parentMenuItem = new MenuItem { Items = { target } };
+                var contextMenu = new ContextMenu { Items = { parentMenuItem } };
                 var window = new Window { Content = new Panel { ContextMenu = contextMenu } };
                 window.ApplyStyling();
                 window.ApplyTemplate();
@@ -317,12 +317,12 @@ namespace Avalonia.Controls.UnitTests
                 MenuItem childMenu2;
                 var menu = new Menu
                 {
-                    Items = new[]
+                    Items =
                     {
                         (topLevelMenu = new MenuItem
                         {
                             Header = "Foo",
-                            Items = new[]
+                            Items =
                             {
                                 (childMenu1 = new MenuItem { Header = "Bar" }),
                                 (childMenu2 = new MenuItem { Header = "Baz" }),
diff --git a/tests/Avalonia.Controls.UnitTests/Presenters/ItemsPresenterTests.cs b/tests/Avalonia.Controls.UnitTests/Presenters/ItemsPresenterTests.cs
index 573ce5834d..ca98991c4b 100644
--- a/tests/Avalonia.Controls.UnitTests/Presenters/ItemsPresenterTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/Presenters/ItemsPresenterTests.cs
@@ -114,7 +114,7 @@ namespace Avalonia.Controls.UnitTests.Presenters
                 var panel = Assert.IsType<StackPanel>(target.Panel);
 
                 var newItems = new[] { "qux", "quux", "corge" };
-                itemsControl.Items = newItems;
+                itemsControl.ItemsSource = newItems;
                 root.LayoutManager.ExecuteLayoutPass();
 
                 AssertContainers(panel, newItems);
@@ -139,7 +139,7 @@ namespace Avalonia.Controls.UnitTests.Presenters
 
             var itemsControl = new ItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = new FuncControlTemplate<ItemsControl>((_, _) => result)
             };
 
diff --git a/tests/Avalonia.Controls.UnitTests/Primitives/PopupRootTests.cs b/tests/Avalonia.Controls.UnitTests/Primitives/PopupRootTests.cs
index 788e6a48bb..fb88c98343 100644
--- a/tests/Avalonia.Controls.UnitTests/Primitives/PopupRootTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/Primitives/PopupRootTests.cs
@@ -67,7 +67,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             using (UnitTestApplication.Start(TestServices.StyledWindow))
             {
                 var window = new Window();
-                var target = new Popup {PlacementMode = PlacementMode.Pointer};
+                var target = new Popup {Placement = PlacementMode.Pointer};
                 var child = new Control();
 
                 window.Content = target;
diff --git a/tests/Avalonia.Controls.UnitTests/Primitives/PopupTests.cs b/tests/Avalonia.Controls.UnitTests/Primitives/PopupTests.cs
index bc1225e0e8..1e22aa9129 100644
--- a/tests/Avalonia.Controls.UnitTests/Primitives/PopupTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/Primitives/PopupTests.cs
@@ -207,7 +207,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             using (CreateServices())
             {
-                var target = new Popup() {PlacementMode = PlacementMode.Pointer};
+                var target = new Popup() {Placement = PlacementMode.Pointer};
                 var root = PreparedWindow(target);
 
                 target.Open();
@@ -226,7 +226,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             using (CreateServices())
             {
                 var window = PreparedWindow();
-                var target = new Popup() {PlacementMode = PlacementMode.Pointer};
+                var target = new Popup() {Placement = PlacementMode.Pointer};
 
                 window.Content = target;
 
@@ -249,7 +249,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             using (CreateServices())
             {
                 var window = PreparedWindow();
-                var target = new Popup() {PlacementMode = PlacementMode.Pointer};
+                var target = new Popup() {Placement = PlacementMode.Pointer};
 
                 window.Content = target;
                 window.ApplyTemplate();
@@ -274,7 +274,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             using (CreateServices())
             {
                 var window = PreparedWindow();
-                var target = new Popup() { PlacementMode = PlacementMode.Pointer };
+                var target = new Popup() { Placement = PlacementMode.Pointer };
 
                 window.Content = target;
                 window.ApplyTemplate();
@@ -395,7 +395,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var item = new Border();
                 var root = PreparedWindow(target = new PopupItemsControl
                 {
-                    Items = new[] { item },
+                    Items = { item },
                     Template = new FuncControlTemplate<PopupItemsControl>(PopupItemsControlTemplate),
                 }); ;
                 root.Show();
@@ -490,7 +490,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var item = new Border();
                 var root = PreparedWindow(target = new PopupItemsControl
                 {
-                    Items = new[] { item },
+                    Items = { item },
                     Template = new FuncControlTemplate<PopupItemsControl>(PopupItemsControlTemplate),
                 });
                 root.Show();
@@ -742,7 +742,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 {
                     Width = 400,
                     Height = 200,
-                    PlacementMode = PlacementMode.Pointer
+                    Placement = PlacementMode.Pointer
                 };
                 var window = PreparedWindow(popup);
                 window.Show();
@@ -791,7 +791,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var popup = new Popup()
                 {
                     PlacementTarget = placementTarget,
-                    PlacementMode = PlacementMode.Bottom,
+                    Placement = PlacementMode.Bottom,
                     Width = 10,
                     Height = 10
                 };
@@ -852,7 +852,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var popup = new Popup()
                 {
                     PlacementTarget = placementTarget,
-                    PlacementMode = PlacementMode.Pointer,
+                    Placement = PlacementMode.Pointer,
                     Width = 10,
                     Height = 10
                 };
@@ -907,7 +907,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var popup = new Popup()
                 {
                     PlacementTarget = placementTarget,
-                    PlacementMode = PlacementMode.Bottom,
+                    Placement = PlacementMode.Bottom,
                     Width = 10,
                     Height = 10
                 };
@@ -967,7 +967,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var popup = new Popup()
                 {
                     PlacementTarget = placementTarget,
-                    PlacementMode = PlacementMode.Pointer,
+                    Placement = PlacementMode.Pointer,
                     Width = 10,
                     Height = 10
                 };
@@ -1020,7 +1020,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                     Width = 20,
                     Height = 20,
                     PlacementTarget = parentPopup, 
-                    PlacementMode = PlacementMode.AnchorAndGravity,
+                    Placement = PlacementMode.AnchorAndGravity,
                     PlacementAnchor = PopupAnchor.TopLeft,
                     PlacementGravity = PopupGravity.BottomRight
                 };
diff --git a/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs b/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs
index 7d129d987e..3fa2bb515d 100644
--- a/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs
@@ -43,7 +43,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -61,7 +61,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -82,7 +82,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -105,7 +105,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -127,7 +127,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new ListBox();
             target.BeginInit();
-            target.Items = items;
+            target.ItemsSource = items;
             target.Template = Template();
             target.EndInit();
 
@@ -144,7 +144,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             };
 
             var target = new ListBox();
-            target.Items = items;
+            target.ItemsSource = items;
             target.Template = Template();
             target.DataContext = new object();
 
@@ -163,7 +163,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new ListBox();
             target.BeginInit();
             target.SelectionMode = SelectionMode.Single | SelectionMode.AlwaysSelected;
-            target.Items = items;
+            target.ItemsSource = items;
             target.Template = Template();
             target.EndInit();
 
@@ -184,7 +184,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             listBox.SelectedIndex = 1;
             var items = new AvaloniaList<string>();
-            listBox.Items = items;
+            listBox.ItemsSource = items;
             items.Add("A");
             items.Add("B");
             items.Add("C");
@@ -202,7 +202,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var listBox = new ListBox
             {
                 SelectionMode = SelectionMode.Single,
-                Items = new[] { "foo", "bar", "baz" },
+                ItemsSource = new[] { "foo", "bar", "baz" },
                 SelectedIndex = 1
             };
 
@@ -220,7 +220,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var listBox = new ListBox
             {
                 SelectionMode = SelectionMode.Single,
-                Items = new[] { "foo", "bar", "baz" },
+                ItemsSource = new[] { "foo", "bar", "baz" },
                 SelectedIndex = 2
             };
 
@@ -240,7 +240,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var listBox = new ListBox
             {
                 SelectionMode = SelectionMode.Single,
-                Items = new[] { "foo", "bar", "baz" },
+                ItemsSource = new[] { "foo", "bar", "baz" },
                 SelectedItem = "bar"
             };
 
@@ -259,7 +259,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var listBox = new ListBox
             {
                 SelectionMode = SelectionMode.Multiple,
-                Items = new[] { "foo", "bar", "baz" },
+                ItemsSource = new[] { "foo", "bar", "baz" },
             };
 
             var selected = new[] { "foo", "bar" };
@@ -282,7 +282,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var listBox = new ListBox
             {
                 SelectionMode = SelectionMode.Multiple,
-                Items = new[] { "foo", "bar", "baz" },
+                ItemsSource = new[] { "foo", "bar", "baz" },
             };
 
             var selected = new[] { "foo", "bar" };
@@ -308,7 +308,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             {
                 SelectionMode = SelectionMode.Single | SelectionMode.AlwaysSelected,
 
-                Items = new[] { "foo", "bar", "baz" },
+                ItemsSource = new[] { "foo", "bar", "baz" },
                 SelectedIndex = 1
             };
 
@@ -331,7 +331,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -353,7 +353,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -376,7 +376,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -403,7 +403,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -430,7 +430,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -451,7 +451,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -487,7 +487,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -509,7 +509,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -519,7 +519,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             Assert.Equal(items[1], target.SelectedItem);
             Assert.Equal(1, target.SelectedIndex);
 
-            target.Items = null;
+            target.ItemsSource = null;
 
             Assert.Null(target.SelectedItem);
             Assert.Equal(-1, target.SelectedIndex);
@@ -536,7 +536,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -575,7 +575,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new TestSelector
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
                 SelectionMode = SelectionMode.AlwaysSelected,
             };
@@ -611,7 +611,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl();
             target.BeginInit();
-            target.Items = items;
+            target.ItemsSource = items;
             target.Template = Template();
             target.EndInit();
 
@@ -648,7 +648,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -684,7 +684,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -722,7 +722,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -749,7 +749,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -779,7 +779,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -807,7 +807,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -839,7 +839,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -868,7 +868,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
                 SelectedIndex = 1,
             };
@@ -896,7 +896,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new TestSelector
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -932,7 +932,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new TestSelector
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -968,7 +968,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new TestSelector
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
                 SelectionMode = SelectionMode.AlwaysSelected,
             };
@@ -1004,7 +1004,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new TestSelector
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
                 SelectionMode = SelectionMode.AlwaysSelected,
             };
@@ -1041,7 +1041,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -1078,7 +1078,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             ((ISupportInitialize)target).BeginInit();
             target.SelectedIndex = 1;
-            target.Items = items;
+            target.ItemsSource = items;
             ((ISupportInitialize)target).EndInit();
 
             Prepare(target);
@@ -1096,7 +1096,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             ((ISupportInitialize)target).BeginInit();
             target.SelectedItem = "Bar";
-            target.Items = items;
+            target.ItemsSource = items;
             ((ISupportInitialize)target).EndInit();
 
             Prepare(target);
@@ -1127,7 +1127,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var itemsBinding = new Binding("Child.Items");
             var selectedBinding = new Binding("Child.SelectedItem");
 
-            target.Bind(SelectingItemsControl.ItemsProperty, itemsBinding);
+            target.Bind(SelectingItemsControl.ItemsSourceProperty, itemsBinding);
             target.Bind(SelectingItemsControl.SelectedItemProperty, selectedBinding);
 
             Assert.Equal(1, target.SelectedIndex);
@@ -1163,13 +1163,13 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var root = new SelectingItemsControl
             {
                 Template = Template(),
-                Items = new Control[]
+                ItemsSource = new Control[]
                 {
                     new Border(),
                     nested = new ListBox
                     {
                         Template = Template(),
-                        Items = new[] { "foo", "bar" },
+                        ItemsSource = new[] { "foo", "bar" },
                         SelectedIndex = 1,
                     }
                 },
@@ -1197,7 +1197,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = new[] { "Foo", "Bar", "Baz " },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz " },
                 };
                 AvaloniaLocator.CurrentMutable.Bind<PlatformHotkeyConfiguration>().ToConstant(new Mock<PlatformHotkeyConfiguration>().Object);
                 Prepare(target);
@@ -1221,7 +1221,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = items,
+                    ItemsSource = items,
                 };
                 AvaloniaLocator.CurrentMutable.Bind<PlatformHotkeyConfiguration>().ToConstant(new Mock<PlatformHotkeyConfiguration>().Object);
                 Prepare(target);
@@ -1245,7 +1245,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             itemsMock.Object.AddRange(new[] { "Foo", "Bar", "Baz" });
             var target = new SelectingItemsControl
             {
-                Items = itemsMock.Object
+                ItemsSource = itemsMock.Object
             };
 
             target.SelectedIndex = 1;
@@ -1268,7 +1268,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             target.BeginInit();
             root.Child = target;
 
-            DelayedBinding.Add(target, ItemsControl.ItemsProperty, new Binding(nameof(RootWithItems.Items)));
+            DelayedBinding.Add(target, ItemsControl.ItemsSourceProperty, new Binding(nameof(RootWithItems.Items)));
             DelayedBinding.Add(target, ListBox.SelectedItemProperty, new Binding(nameof(RootWithItems.Selected)));
             target.EndInit();
             root.EndInit();
@@ -1299,7 +1299,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var itemsBinding = new Binding("Child.Items");
             var selectedIndBinding = new Binding("Child.SelectedIndex");
 
-            target.Bind(SelectingItemsControl.ItemsProperty, itemsBinding);
+            target.Bind(SelectingItemsControl.ItemsSourceProperty, itemsBinding);
             target.Bind(SelectingItemsControl.SelectedIndexProperty, selectedIndBinding);
 
             Assert.Equal(1, target.SelectedIndex);
@@ -1318,7 +1318,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = new[] { "Foo", "Bar", "Baz", "Foo", "Bar", "Baz" },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz", "Foo", "Bar", "Baz" },
                 };
                 AvaloniaLocator.CurrentMutable.Bind<PlatformHotkeyConfiguration>().ToConstant(new Mock<PlatformHotkeyConfiguration>().Object);
                 Prepare(target);
@@ -1336,7 +1336,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = new[] { "Foo", "Bar", "Baz", "Foo", "Bar", "Baz" },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz", "Foo", "Bar", "Baz" },
                 };
                 AvaloniaLocator.CurrentMutable.Bind<PlatformHotkeyConfiguration>().ToConstant(new Mock<PlatformHotkeyConfiguration>().Object);
                 Prepare(target);
@@ -1359,7 +1359,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new ListBox
             {
                 Template = Template(),
-                Items = items,
+                ItemsSource = items,
                 SelectedIndex = 1,
             };
 
@@ -1384,7 +1384,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new ListBox
             {
                 Template = Template(),
-                Items = items,
+                ItemsSource = items,
                 SelectedIndex = 1,
             };
 
@@ -1405,14 +1405,14 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var other = new ListBox
             {
                 Template = Template(),
-                Items = items,
+                ItemsSource = items,
                 SelectionMode = SelectionMode.AlwaysSelected,
             };
 
             var target = new ListBox
             {
                 Template = Template(),
-                Items = items,
+                ItemsSource = items,
                 [!ListBox.SelectedIndexProperty] = other[!ListBox.SelectedIndexProperty],
             };
 
@@ -1434,14 +1434,14 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var other = new ListBox
             {
                 Template = Template(),
-                Items = items,
+                ItemsSource = items,
                 SelectionMode = SelectionMode.AlwaysSelected,
             };
 
             var target = new ListBox
             {
                 Template = Template(),
-                Items = items,
+                ItemsSource = items,
                 [!ListBox.SelectedItemProperty] = other[!ListBox.SelectedItemProperty],
             };
 
@@ -1468,7 +1468,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new ListBox
             {
                 Template = Template(),
-                Items = items,
+                ItemsSource = items,
                 SelectedIndex = 1,
             };
 
@@ -1493,7 +1493,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new ListBox
             {
                 Template = Template(),
-                Items = items,
+                ItemsSource = items,
             };
 
             var raised = false;
@@ -1518,7 +1518,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new ListBox
             {
                 Template = Template(),
-                Items = items,
+                ItemsSource = items,
             };
 
             var raised = false;
@@ -1540,7 +1540,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
                 var target = new ListBox
                 {
-                    Items = items,
+                    ItemsSource = items,
                     ItemTemplate = new FuncDataTemplate<string>((x, _) =>
                         new TextBlock
                         {
@@ -1582,7 +1582,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new ListBox
             {
                 Template = Template(),
-                Items = items,
+                ItemsSource = items,
                 SelectedIndex = 2,
             };
 
@@ -1614,7 +1614,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new ListBox
             {
                 Template = Template(),
-                Items = items,
+                ItemsSource = items,
                 SelectedIndex = 2,
             };
 
@@ -1645,7 +1645,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new ListBox
             {
                 Template = Template(),
-                Items = items,
+                ItemsSource = items,
                 AutoScrollToSelectedItem = false,
             };
 
@@ -1671,7 +1671,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             target.BeginInit();
             target.Template = Template();
-            target.Items = new[] { "Foo", "Bar", "Baz" };
+            target.ItemsSource = new[] { "Foo", "Bar", "Baz" };
             target.SelectedItems = selectedItems;
             target.SelectedItem = "Bar";
             target.EndInit();
@@ -1691,7 +1691,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new TestSelector
             {
                 Template = Template(),
-                Items = new[]
+                Items =
                 {
                     new ListBoxItem { Focusable = false },
                     new ListBoxItem { Focusable = false },
@@ -1713,7 +1713,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new TestSelector
             {
                 Template = Template(),
-                Items = new[]
+                Items =
                 {
                     new ListBoxItem(),
                     new ListBoxItem { Focusable = false },
@@ -1733,7 +1733,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new TestSelector
             {
                 Template = Template(),
-                Items = new[]
+                Items =
                 {
                     new ListBoxItem { Focusable = false },
                     new ListBoxItem(),
@@ -1753,7 +1753,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new TestSelector
             {
                 Template = Template(),
-                Items = new[]
+                Items =
                 {
                     new ListBoxItem { Focusable = false },
                     new ListBoxItem { Focusable = false },
@@ -1776,7 +1776,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new TestSelector
             {
                 Template = Template(),
-                Items = new[]
+                Items =
                 {
                     new ListBoxItem { Focusable = false },
                     new ListBoxItem { Focusable = false },
@@ -1800,7 +1800,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new TestSelector
             {
                 Template = Template(),
-                Items = new[]
+                Items =
                 {
                     new ListBoxItem(),
                     new ListBoxItem { IsEnabled = false },
@@ -1831,7 +1831,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 second
             };
 
-            target.Items = items;
+            target.ItemsSource = items;
 
             Prepare(target);
 
@@ -1878,7 +1878,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new ListBox
             {
-                [!ListBox.ItemsProperty] = new Binding("Items"),
+                [!ListBox.ItemsSourceProperty] = new Binding("Items"),
                 [!ListBox.SelectedIndexProperty] = new Binding("SelectedIndex"),
                 DataContext = vm,
             };
@@ -1906,7 +1906,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new ListBox
             {
-                [!ListBox.ItemsProperty] = new Binding("Items"),
+                [!ListBox.ItemsSourceProperty] = new Binding("Items"),
                 [!ListBox.SelectedItemsProperty] = new Binding("SelectedItems"),
                 DataContext = vm,
             };
@@ -1926,7 +1926,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             using var app = Start();
             var target = new SelectingItemsControl
             {
-                Items = new[] { "foo", "bar", "baz"},
+                ItemsSource = new[] { "foo", "bar", "baz"},
                 SelectedItem = "bar",
             };
 
@@ -1935,7 +1935,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             Assert.Equal(1, target.SelectedIndex);
             Assert.Equal("bar", target.SelectedItem);
 
-            target.Items = new[] { "qux", "foo", "bar" };
+            target.ItemsSource = new[] { "qux", "foo", "bar" };
 
             Assert.Equal(2, target.SelectedIndex);
             Assert.Equal("bar", target.SelectedItem);
@@ -1947,7 +1947,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             using var app = Start();
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar", "baz" },
+                ItemsSource = new[] { "foo", "bar", "baz" },
             };
 
             var raised = 0;
@@ -1976,7 +1976,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             using var app = Start();
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar", "baz" },
+                ItemsSource = new[] { "foo", "bar", "baz" },
             };
 
             var raised = 0;
@@ -2007,13 +2007,13 @@ namespace Avalonia.Controls.UnitTests.Primitives
             // Simulates problem with TabStrip and Carousel with bound SelectedIndex.
             var tabStrip = new TestSelector 
             { 
-                Items = items, 
+                ItemsSource = items, 
                 SelectionMode = SelectionMode.AlwaysSelected,
             };
 
             var carousel = new TestSelector
             {
-                Items = items,
+                ItemsSource = items,
                 [!Carousel.SelectedIndexProperty] = tabStrip[!TabStrip.SelectedIndexProperty],
             };
 
@@ -2048,13 +2048,13 @@ namespace Avalonia.Controls.UnitTests.Primitives
             // Simulates problem with TabStrip and Carousel with bound SelectedItem.
             var tabStrip = new TestSelector
             {
-                Items = items,
+                ItemsSource = items,
                 SelectionMode = SelectionMode.AlwaysSelected,
             };
 
             var carousel = new TestSelector
             {
-                Items = items,
+                ItemsSource = items,
                 [!Carousel.SelectedItemProperty] = tabStrip[!TabStrip.SelectedItemProperty],
             };
 
@@ -2100,7 +2100,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
                 var target = new SelectingItemsControl
                 {
-                    Items = items, 
+                    ItemsSource = items, 
                     Template = Template(), 
                     IsTextSearchEnabled = false
                 };
diff --git a/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests_AutoSelect.cs b/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests_AutoSelect.cs
index c3e37666f7..71bd0933a1 100644
--- a/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests_AutoSelect.cs
+++ b/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests_AutoSelect.cs
@@ -16,7 +16,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar" },
+                ItemsSource = new[] { "foo", "bar" },
                 Template = Template(),
             };
 
@@ -32,7 +32,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var items = new AvaloniaList<string>();
             var target = new TestSelector
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -50,7 +50,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var items = new ResetOnAdd();
             var target = new TestSelector
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -68,7 +68,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new TestSelector
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -87,7 +87,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new TestSelector
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
@@ -106,7 +106,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var items = new AvaloniaList<string>(new[] { "foo", "bar" });
             var target = new TestSelector
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
             };
 
diff --git a/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests_Multiple.cs b/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests_Multiple.cs
index 0b72baf336..1108780d9a 100644
--- a/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests_Multiple.cs
+++ b/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests_Multiple.cs
@@ -27,7 +27,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar" },
+                ItemsSource = new[] { "foo", "bar" },
                 Template = Template(),
             };
 
@@ -42,7 +42,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar" },
+                ItemsSource = new[] { "foo", "bar" },
                 Template = Template(),
             };
 
@@ -57,7 +57,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar" },
+                ItemsSource = new[] { "foo", "bar" },
                 Template = Template(),
             };
 
@@ -75,7 +75,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar", "baz" },
+                ItemsSource = new[] { "foo", "bar", "baz" },
                 Template = Template(),
             };
 
@@ -94,7 +94,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             // Issue #2565.
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar", "baz" },
+                ItemsSource = new[] { "foo", "bar", "baz" },
                 Template = Template(),
             };
 
@@ -112,7 +112,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar" },
+                ItemsSource = new[] { "foo", "bar" },
                 Template = Template(),
             };
 
@@ -129,7 +129,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar" },
+                ItemsSource = new[] { "foo", "bar" },
                 Template = Template(),
             };
 
@@ -157,7 +157,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar" },
+                ItemsSource = new[] { "foo", "bar" },
                 Template = Template(),
             };
 
@@ -179,7 +179,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar" },
+                ItemsSource = new[] { "foo", "bar" },
                 Template = Template(),
             };
 
@@ -200,26 +200,23 @@ namespace Avalonia.Controls.UnitTests.Primitives
         [Fact]
         public void Adding_SelectedItems_Should_Set_Item_IsSelected()
         {
-            var items = new[]
-            {
-                new ListBoxItem(),
-                new ListBoxItem(),
-                new ListBoxItem(),
-            };
-
             var target = new TestSelector
             {
-                Items = items,
+                Items = 
+                {
+                    new ListBoxItem(),
+                    new ListBoxItem(),
+                    new ListBoxItem(),
+                },
                 Template = Template(),
             };
 
             target.ApplyTemplate();
             target.Presenter.ApplyTemplate();
-            target.SelectedItems.Add(items[0]);
-            target.SelectedItems.Add(items[1]);
-
-            var foo = target.Presenter.Panel.Children[0];
+            target.SelectedItems.Add(target.Items[0]);
+            target.SelectedItems.Add(target.Items[1]);
 
+            var items = target.Items.Cast<ListBoxItem>().ToList();
             Assert.True(items[0].IsSelected);
             Assert.True(items[1].IsSelected);
             Assert.False(items[2].IsSelected);
@@ -228,23 +225,22 @@ namespace Avalonia.Controls.UnitTests.Primitives
         [Fact]
         public void Assigning_SelectedItems_Should_Set_Item_IsSelected()
         {
-            var items = new[]
-            {
-                new ListBoxItem(),
-                new ListBoxItem(),
-                new ListBoxItem(),
-            };
-
             var target = new TestSelector
             {
-                Items = items,
+                Items =
+                {
+                    new ListBoxItem(),
+                    new ListBoxItem(),
+                    new ListBoxItem(),
+                },
                 Template = Template(),
             };
 
             target.ApplyTemplate();
             target.Presenter.ApplyTemplate();
-            target.SelectedItems = new AvaloniaList<object> { items[0], items[1] };
+            target.SelectedItems = new AvaloniaList<object> { target.Items[0], target.Items[1] };
 
+            var items = target.Items.Cast<ListBoxItem>().ToList();
             Assert.True(items[0].IsSelected);
             Assert.True(items[1].IsSelected);
             Assert.False(items[2].IsSelected);
@@ -253,25 +249,24 @@ namespace Avalonia.Controls.UnitTests.Primitives
         [Fact]
         public void Removing_SelectedItems_Should_Clear_Item_IsSelected()
         {
-            var items = new[]
-            {
-                new ListBoxItem(),
-                new ListBoxItem(),
-                new ListBoxItem(),
-            };
-
             var target = new TestSelector
             {
-                Items = items,
+                Items =
+                {
+                    new ListBoxItem(),
+                    new ListBoxItem(),
+                    new ListBoxItem(),
+                },
                 Template = Template(),
             };
 
             target.ApplyTemplate();
             target.Presenter.ApplyTemplate();
-            target.SelectedItems.Add(items[0]);
-            target.SelectedItems.Add(items[1]);
-            target.SelectedItems.Remove(items[1]);
+            target.SelectedItems.Add(target.Items[0]);
+            target.SelectedItems.Add(target.Items[1]);
+            target.SelectedItems.Remove(target.Items[1]);
 
+            var items = target.Items.Cast<ListBoxItem>().ToList();
             Assert.True(items[0].IsSelected);
             Assert.False(items[1].IsSelected);
         }
@@ -279,25 +274,24 @@ namespace Avalonia.Controls.UnitTests.Primitives
         [Fact]
         public void Reassigning_SelectedItems_Should_Clear_Item_IsSelected()
         {
-            var items = new[]
-            {
-                new ListBoxItem(),
-                new ListBoxItem(),
-                new ListBoxItem(),
-            };
-
             var target = new TestSelector
             {
-                Items = items,
+                Items = 
+                {
+                    new ListBoxItem(),
+                    new ListBoxItem(),
+                    new ListBoxItem(),
+                },
                 Template = Template(),
             };
 
             target.ApplyTemplate();
-            target.SelectedItems.Add(items[0]);
-            target.SelectedItems.Add(items[1]);
+            target.SelectedItems.Add(target.Items[0]);
+            target.SelectedItems.Add(target.Items[1]);
 
-            target.SelectedItems = new AvaloniaList<object> { items[0], items[1] };
+            target.SelectedItems = new AvaloniaList<object> { target.Items[0], target.Items[1] };
 
+            var items = target.Items.Cast<ListBoxItem>().ToList();
             Assert.False(items[0].IsSelected);
             Assert.False(items[1].IsSelected);
         }
@@ -307,7 +301,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar", "baz" },
+                ItemsSource = new[] { "foo", "bar", "baz" },
                 Template = Template(),
             };
 
@@ -329,7 +323,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[]
+                ItemsSource = new[]
                 {
                     "foo",
                     "bar",
@@ -353,7 +347,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[]
+                ItemsSource = new[]
                 {
                     "foo",
                     "bar",
@@ -378,7 +372,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[]
+                ItemsSource = new[]
                 {
                     "foo",
                     "bar",
@@ -404,7 +398,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar", "baz", "qux" },
+                ItemsSource = new[] { "foo", "bar", "baz", "qux" },
                 Template = Template(),
                 SelectedIndex = 0,
                 SelectionMode = SelectionMode.Multiple,
@@ -427,7 +421,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar", "baz", "foo", "bar", "baz" },
+                ItemsSource = new[] { "foo", "bar", "baz", "foo", "bar", "baz" },
                 Template = Template(),
                 SelectedIndex = 0,
                 SelectionMode = SelectionMode.Multiple,
@@ -450,7 +444,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar", "baz" },
+                ItemsSource = new[] { "foo", "bar", "baz" },
                 Template = Template(),
             };
 
@@ -471,7 +465,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar", "baz" },
+                ItemsSource = new[] { "foo", "bar", "baz" },
                 Template = Template(),
             };
 
@@ -536,8 +530,8 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 Mode = BindingMode.OneWay,
             };
 
-            // Bind Items and SelectedItems to the VM.
-            target.Bind(TestSelector.ItemsProperty, itemsBinding);
+            // Bind ItemsSource and SelectedItems to the VM.
+            target.Bind(TestSelector.ItemsSourceProperty, itemsBinding);
             target.Bind(TestSelector.SelectedItemsProperty, selectedItemsBinding);
 
             // Set DataContext and SelectedIndex
@@ -576,8 +570,8 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 Mode = BindingMode.OneWay,
             };
 
-            // Bind Items and Selection to the VM.
-            target.Bind(TestSelector.ItemsProperty, itemsBinding);
+            // Bind ItemsSource and Selection to the VM.
+            target.Bind(TestSelector.ItemsSourceProperty, itemsBinding);
             target.Bind(TestSelector.SelectionProperty, selectionBinding);
 
             // Set DataContext and SelectedIndex
@@ -610,9 +604,9 @@ namespace Avalonia.Controls.UnitTests.Primitives
             };
 
             var itemsBinding = new Binding { Path = "Items" };
-            target.Bind(TestSelector.ItemsProperty, itemsBinding);
+            target.Bind(TestSelector.ItemsSourceProperty, itemsBinding);
 
-            Assert.Same(data.Items, target.Items);
+            Assert.Same(data.Items, target.ItemsSource);
 
             target.SelectedItems.Add("bar");
             target.DataContext = null;
@@ -629,7 +623,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             {
                 DataContext = items,
                 Template = Template(),
-                Items = items,
+                ItemsSource = items,
             };
 
             var called = false;
@@ -653,7 +647,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new TestSelector
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
                 SelectedItem = "bar",
             };
@@ -679,7 +673,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new TestSelector
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
                 SelectedItem = "bar",
             };
@@ -708,7 +702,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = new[] { "Foo", "Bar", "Baz" },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz" },
                     SelectionMode = SelectionMode.Multiple,
                     Width = 100,
                     Height = 100,
@@ -733,7 +727,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = new[] { "Foo", "Bar", "Baz", "Qux" },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz", "Qux" },
                     SelectionMode = SelectionMode.Multiple,
                     Width = 100,
                     Height = 100,
@@ -791,7 +785,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = new[] { "Foo", "Bar", "Baz", "Qux" },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz", "Qux" },
                     SelectionMode = SelectionMode.Multiple,
                     Width = 100,
                     Height = 100,
@@ -825,7 +819,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = new[] { "Foo", "Bar", "Baz" },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz" },
                     SelectionMode = SelectionMode.Multiple,
                     Width = 100,
                     Height = 100,
@@ -856,7 +850,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = new[] { "Foo", "Bar", "Baz", "Foo", "Bar", "Baz" },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz", "Foo", "Bar", "Baz" },
                     SelectionMode = SelectionMode.Multiple,
                     Width = 100,
                     Height = 100,
@@ -884,7 +878,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = new[] { "Foo", "Bar", "Baz", "Foo", "Bar", "Baz" },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz", "Foo", "Bar", "Baz" },
                     SelectionMode = SelectionMode.Multiple,
                     Width = 100,
                     Height = 100,
@@ -912,7 +906,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = new[] { "Foo", "Bar", "Baz", "Foo", "Bar", "Baz" },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz", "Foo", "Bar", "Baz" },
                     SelectionMode = SelectionMode.Multiple,
                     Width = 100,
                     Height = 100,
@@ -940,7 +934,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = new[] { "Foo", "Bar", "Baz", "Qux" },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz", "Qux" },
                     SelectionMode = SelectionMode.Multiple,
                     Width = 100,
                     Height = 100,
@@ -992,7 +986,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = new[] { "Foo", "Bar", "Baz", "Foo", "Bar", "Baz" },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz", "Foo", "Bar", "Baz" },
                     SelectionMode = SelectionMode.Multiple,
                     Width = 100,
                     Height = 100,
@@ -1026,7 +1020,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new TestSelector
             {
                 Template = Template(),
-                Items = new[] { "Foo", "Bar", "Baz" },
+                ItemsSource = new[] { "Foo", "Bar", "Baz" },
                 SelectionMode = SelectionMode.Multiple,
             };
 
@@ -1045,7 +1039,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new TestSelector
             {
                 Template = Template(),
-                Items = new[] { "Foo", "Bar", "Baz" },
+                ItemsSource = new[] { "Foo", "Bar", "Baz" },
                 SelectionMode = SelectionMode.Multiple,
             };
 
@@ -1059,7 +1053,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             target.SelectAll();
 
             Assert.NotNull(receivedArgs);
-            Assert.Equal(target.Items, receivedArgs.AddedItems);
+            Assert.Equal(target.ItemsSource, receivedArgs.AddedItems);
             Assert.Empty(receivedArgs.RemovedItems);
         }
 
@@ -1069,7 +1063,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new TestSelector
             {
                 Template = Template(),
-                Items = new[] { "Foo", "Bar", "Baz" },
+                ItemsSource = new[] { "Foo", "Bar", "Baz" },
                 SelectionMode = SelectionMode.Multiple,
                 SelectedIndex = 0,
             };
@@ -1089,7 +1083,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new TestSelector
             {
                 Template = Template(),
-                Items = new[] { "Foo", "Bar", "Baz", "Foo", "Bar", "Baz" },
+                ItemsSource = new[] { "Foo", "Bar", "Baz", "Foo", "Bar", "Baz" },
                 SelectionMode = SelectionMode.Multiple,
             };
 
@@ -1113,7 +1107,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new ListBox
             {
                 Template = Template(),
-                Items = items,
+                ItemsSource = items,
                 SelectionMode = SelectionMode.Multiple,
                 Width = 100,
                 Height = 100,
@@ -1145,7 +1139,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new TestSelector
             {
                 Template = Template(),
-                Items = items,
+                ItemsSource = items,
                 SelectionMode = SelectionMode.Multiple,
             };
 
@@ -1178,7 +1172,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new ListBox
             {
                 Template = Template(),
-                Items = items,
+                ItemsSource = items,
                 SelectionMode = SelectionMode.Multiple,
                 Width = 100,
                 Height = 100,
@@ -1209,7 +1203,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var target = new ListBox
             {
                 Template = Template(),
-                Items = items,
+                ItemsSource = items,
                 SelectionMode = SelectionMode.Multiple,
                 Width = 100,
                 Height = 100,
@@ -1232,7 +1226,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = new[] { "Foo", "Bar", "Baz" },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz" },
                     ItemTemplate = new FuncDataTemplate<string>((x, _) => new TextBlock { Width = 20, Height = 10 }),
                     SelectionMode = SelectionMode.Multiple,
                     Width = 100,
@@ -1262,7 +1256,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = new[] { "Foo", "Bar", "Baz" },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz" },
                     ItemTemplate = new FuncDataTemplate<string>((x, _) => new TextBlock { Width = 20, Height = 10 }),
                     SelectionMode = SelectionMode.Multiple,
                     Width = 100,
@@ -1290,7 +1284,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = new[] { "Foo", "Bar", "Baz" },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz" },
                     ItemTemplate = new FuncDataTemplate<string>((x, _) => new TextBlock { Width = 20, Height = 10 }),
                     SelectionMode = SelectionMode.Multiple,
                     Width = 100,
@@ -1315,27 +1309,25 @@ namespace Avalonia.Controls.UnitTests.Primitives
         [Fact]
         public void Adding_Selected_ItemContainers_Should_Update_Selection()
         {
-            var items = new AvaloniaList<ItemContainer>(new[]
-            {
-                new ItemContainer(),
-                new ItemContainer(),
-            });
-
             var target = new TestSelector
             {
-                Items = items,
+                Items =
+                {
+                    new ItemContainer(),
+                    new ItemContainer(),
+                },
                 SelectionMode = SelectionMode.Multiple,
                 Template = Template(),
             };
 
             target.ApplyTemplate();
             target.Presenter.ApplyTemplate();
-            items.Add(new ItemContainer { IsSelected = true });
-            items.Add(new ItemContainer { IsSelected = true });
+            target.Items.Add(new ItemContainer { IsSelected = true });
+            target.Items.Add(new ItemContainer { IsSelected = true });
 
             Assert.Equal(2, target.SelectedIndex);
-            Assert.Equal(items[2], target.SelectedItem);
-            Assert.Equal(new[] { items[2], items[3] }, target.SelectedItems);
+            Assert.Equal(target.Items[2], target.SelectedItem);
+            Assert.Equal(new[] { target.Items[2], target.Items[3] }, target.SelectedItems);
         }
 
         [Fact]
@@ -1346,7 +1338,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = new[] { "Foo", "Bar", "Baz" },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz" },
                     ItemTemplate = new FuncDataTemplate<string>((x, _) => new TextBlock { Width = 20, Height = 10 }),
                     SelectionMode = SelectionMode.Multiple,
                     Width = 100,
@@ -1373,7 +1365,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var target = new ListBox
                 {
                     Template = Template(),
-                    Items = new[] { "Foo", "Bar", "Baz" },
+                    ItemsSource = new[] { "Foo", "Bar", "Baz" },
                     ItemTemplate = new FuncDataTemplate<string>((x, _) => new TextBlock { Width = 20, Height = 10 }),
                     SelectionMode = SelectionMode.Multiple,
                     Width = 100,
@@ -1397,7 +1389,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar" },
+                ItemsSource = new[] { "foo", "bar" },
                 Template = Template(),
             };
 
@@ -1412,7 +1404,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar" },
+                ItemsSource = new[] { "foo", "bar" },
                 Template = Template(),
             };
 
@@ -1429,7 +1421,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar" },
+                ItemsSource = new[] { "foo", "bar" },
                 Template = Template(),
             };
 
@@ -1442,14 +1434,14 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar" },
+                ItemsSource = new[] { "foo", "bar" },
                 Template = Template(),
             };
 
             var selection = new SelectionModel<string>();
             target.Selection = selection;
 
-            Assert.Same(target.Items, selection.Source);
+            Assert.Same(target.ItemsSource, selection.Source);
         }
 
         [Fact]
@@ -1457,7 +1449,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar" },
+                ItemsSource = new[] { "foo", "bar" },
                 Template = Template(),
             };
 
@@ -1478,7 +1470,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar", "baz" },
+                ItemsSource = new[] { "foo", "bar", "baz" },
                 Template = Template(),
             };
 
@@ -1499,7 +1491,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
         {
             var target = new TestSelector
             {
-                Items = new[] { "foo", "bar" },
+                ItemsSource = new[] { "foo", "bar" },
                 Template = Template(),
             };
 
@@ -1514,16 +1506,14 @@ namespace Avalonia.Controls.UnitTests.Primitives
         [Fact]
         public void Assigning_Selection_Should_Set_Item_IsSelected()
         {
-            var items = new[]
-            {
-                new ListBoxItem(),
-                new ListBoxItem(),
-                new ListBoxItem(),
-            };
-
             var target = new TestSelector
             {
-                Items = items,
+                Items =
+                {
+                    new ListBoxItem(),
+                    new ListBoxItem(),
+                    new ListBoxItem(),
+                },
                 Template = Template(),
             };
 
@@ -1534,6 +1524,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             selection.SelectRange(0, 1);
             target.Selection = selection;
 
+            var items = target.Items.Cast<ListBoxItem>().ToList();
             Assert.True(items[0].IsSelected);
             Assert.True(items[1].IsSelected);
             Assert.False(items[2].IsSelected);
@@ -1546,7 +1537,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
             var target = new TestSelector
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
                 SelectedItem = "bar",
             };
diff --git a/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests_SelectedValue.cs b/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests_SelectedValue.cs
index df81b1faae..e9b8895174 100644
--- a/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests_SelectedValue.cs
+++ b/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests_SelectedValue.cs
@@ -21,7 +21,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var items = TestClass.GetItems();
             var sic = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 SelectedValueBinding = new Binding("Name"),
                 Template = Template()
             };
@@ -37,7 +37,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var items = TestClass.GetItems();
             var sic = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 SelectedValueBinding = new Binding("Name"),
                 Template = Template()
             };
@@ -53,7 +53,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var items = TestClass.GetItems();
             var sic = new ListBox
             {
-                Items = items,
+                ItemsSource = items,
                 SelectedValueBinding = new Binding("Name"),
                 Template = Template()
             };
@@ -78,7 +78,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var items = TestClass.GetItems();
                 var sic = new SelectingItemsControl
                 {
-                    Items = items,
+                    ItemsSource = items,
                     SelectedValueBinding = new Binding("Name"),
                     Template = Template()
                 };
@@ -99,7 +99,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var items = TestClass.GetItems();
                 var sic = new SelectingItemsControl
                 {
-                    Items = items,
+                    ItemsSource = items,
                     SelectedValueBinding = new Binding("Name"),
                     Template = Template()
                 };
@@ -120,7 +120,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var items = TestClass.GetItems();
                 var sic = new SelectingItemsControl
                 {
-                    Items = items,
+                    ItemsSource = items,
                     SelectedValueBinding = new Binding("Name"),
                     Template = Template()
                 };
@@ -143,7 +143,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var items = TestClass.GetItems();
             var sic = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template()
             };
 
@@ -158,7 +158,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var items = TestClass.GetItems();
             var sic = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
                 SelectedValueBinding = new Binding("Name"),
                 SelectedValue = "Item2"
@@ -176,7 +176,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var items = TestClass.GetItems();
             var sic = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
                 SelectedValueBinding = new Binding("Name"),
                 SelectedValue = "Item2"
@@ -197,7 +197,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var items = TestClass.GetItems();
                 var sic = new SelectingItemsControl
                 {
-                    Items = items,
+                    ItemsSource = items,
                     Template = Template(),
                     SelectedValueBinding = new Binding("Name"),
                     SelectedValue = "Item2"
@@ -205,7 +205,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
 
                 Prepare(sic);
 
-                sic.Items = new List<TestClass>
+                sic.ItemsSource = new List<TestClass>
                 {
                     new TestClass("NewItem", string.Empty)
                 };
@@ -224,7 +224,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 var items = TestClass.GetItems();
                 var sic = new SelectingItemsControl
                 {
-                    Items = items,
+                    ItemsSource = items,
                     Template = Template(),
                     SelectedValueBinding = new Binding("Name"),
                 };
@@ -250,7 +250,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             var items = TestClass.GetItems();
             var sic = new SelectingItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = Template(),
                 SelectedValueBinding = new Binding("Name"),
                 SelectedValue = "Item2"
diff --git a/tests/Avalonia.Controls.UnitTests/Primitives/TabStripTests.cs b/tests/Avalonia.Controls.UnitTests/Primitives/TabStripTests.cs
index 05183fe787..d50f6e1d0d 100644
--- a/tests/Avalonia.Controls.UnitTests/Primitives/TabStripTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/Primitives/TabStripTests.cs
@@ -14,90 +14,84 @@ namespace Avalonia.Controls.UnitTests.Primitives
         [Fact]
         public void First_Tab_Should_Be_Selected_By_Default()
         {
-            var items = new[]
-            {
-                new TabItem
-                {
-                    Name = "first"
-                },
-                new TabItem
-                {
-                    Name = "second"
-                },
-            };
-
             var target = new TabStrip
             {
                 Template = new FuncControlTemplate<TabStrip>(CreateTabStripTemplate),
-                Items = items,
+                Items =
+                {
+                    new TabItem
+                    {
+                        Name = "first"
+                    },
+                    new TabItem
+                    {
+                        Name = "second"
+                    },
+                }
             };
 
             target.ApplyTemplate();
 
             Assert.Equal(0, target.SelectedIndex);
-            Assert.Same(items[0], target.SelectedItem);
+            Assert.Same(target.Items[0], target.SelectedItem);
         }
 
         [Fact]
         public void Setting_SelectedItem_Should_Set_Selection()
         {
-            var items = new[]
-            {
-                new TabItem
-                {
-                    Name = "first"
-                },
-                new TabItem
-                {
-                    Name = "second"
-                },
-            };
-
             var target = new TabStrip
             {
                 Template = new FuncControlTemplate<TabStrip>(CreateTabStripTemplate),
-                Items = items,
-                SelectedItem = items[1],
+                Items =
+                {
+                    new TabItem
+                    {
+                        Name = "first"
+                    },
+                    new TabItem
+                    {
+                        Name = "second"
+                    },
+                },             
             };
 
+            target.SelectedItem = target.Items[1];
             target.ApplyTemplate();
 
             Assert.Equal(1, target.SelectedIndex);
-            Assert.Same(items[1], target.SelectedItem);
+            Assert.Same(target.Items[1], target.SelectedItem);
         }
 
         [Fact]
         public void Removing_Selected_Should_Select_First()
         {
-            var items = new ObservableCollection<TabItem>()
-            {
-                new TabItem
-                {
-                    Name = "first"
-                },
-                new TabItem
-                {
-                    Name = "second"
-                },
-                new TabItem
-                {
-                    Name = "3rd"
-                },
-            };
-
             var target = new TabStrip
             {
                 Template = new FuncControlTemplate<TabStrip>(CreateTabStripTemplate),
-                Items = items
+                Items =
+                {
+                    new TabItem
+                    {
+                        Name = "first"
+                    },
+                    new TabItem
+                    {
+                        Name = "second"
+                    },
+                    new TabItem
+                    {
+                        Name = "3rd"
+                    },
+                }
             };
 
             target.ApplyTemplate();
-            target.SelectedItem = items[1];
-            Assert.Same(items[1], target.SelectedItem);
-            items.RemoveAt(1);
+            target.SelectedItem = target.Items[1];
+            Assert.Same(target.Items[1], target.SelectedItem);
+            target.Items.RemoveAt(1);
 
             Assert.Equal(0, target.SelectedIndex);
-            Assert.Same(items[0], target.SelectedItem);
+            Assert.Same(target.Items[0], target.SelectedItem);
             Assert.Same("first", ((TabItem)target.SelectedItem).Name);
         }
 
diff --git a/tests/Avalonia.Controls.UnitTests/TabControlTests.cs b/tests/Avalonia.Controls.UnitTests/TabControlTests.cs
index 0f72b2101a..7440ee4858 100644
--- a/tests/Avalonia.Controls.UnitTests/TabControlTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/TabControlTests.cs
@@ -24,7 +24,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new TabControl
             {
                 Template = TabControlTemplate(),
-                Items = new[]
+                Items =
                 {
                     (selected = new TabItem
                     {
@@ -48,21 +48,17 @@ namespace Avalonia.Controls.UnitTests
         [Fact]
         public void Pre_Selecting_TabItem_Should_Set_SelectedContent_After_It_Was_Added()
         {
+            const string secondContent = "Second";
             var target = new TabControl
             {
                 Template = TabControlTemplate(),
+                Items =
+                {
+                    new TabItem { Header = "First"},
+                    new TabItem { Header = "Second", Content = secondContent, IsSelected = true }
+                },
             };
 
-            const string secondContent = "Second";
-
-            var items = new AvaloniaList<object>
-            {
-                new TabItem { Header = "First"},
-                new TabItem { Header = "Second", Content = secondContent, IsSelected = true }
-            };
-
-            target.Items = items;
-
             ApplyTemplate(target);
 
             Assert.Equal(secondContent, target.SelectedContent);
@@ -71,107 +67,105 @@ namespace Avalonia.Controls.UnitTests
         [Fact]
         public void Logical_Children_Should_Be_TabItems()
         {
-            var items = new[]
-            {
-                new TabItem
-                {
-                    Content = "foo"
-                },
-                new TabItem
-                {
-                    Content = "bar"
-                },
-            };
-
             var target = new TabControl
             {
                 Template = TabControlTemplate(),
-                Items = items,
+                Items =
+                {
+                    new TabItem
+                    {
+                        Content = "foo"
+                    },
+                    new TabItem
+                    {
+                        Content = "bar"
+                    },
+                }
             };
 
-            Assert.Equal(items, target.GetLogicalChildren());
+            Assert.Equal(target.Items, target.GetLogicalChildren().ToList());
             target.ApplyTemplate();
-            Assert.Equal(items, target.GetLogicalChildren());
+            Assert.Equal(target.Items, target.GetLogicalChildren().ToList());
         }
 
         [Fact]
         public void Removal_Should_Set_First_Tab()
         {
-            var collection = new ObservableCollection<TabItem>()
-            {
-                new TabItem
-                {
-                    Name = "first",
-                    Content = "foo",
-                },
-                new TabItem
-                {
-                    Name = "second",
-                    Content = "bar",
-                },
-                new TabItem
-                {
-                    Name = "3rd",
-                    Content = "barf",
-                },
-            };
-
             var target = new TabControl
             {
                 Template = TabControlTemplate(),
-                Items = collection,
+                Items =
+                {
+                    new TabItem
+                    {
+                        Name = "first",
+                        Content = "foo",
+                    },
+                    new TabItem
+                    {
+                        Name = "second",
+                        Content = "bar",
+                    },
+                    new TabItem
+                    {
+                        Name = "3rd",
+                        Content = "barf",
+                    },
+                }
             };
 
             Prepare(target);
-            target.SelectedItem = collection[1];
+            target.SelectedItem = target.Items[1];
 
-            Assert.Same(collection[1], target.SelectedItem);
-            Assert.Equal(collection[1].Content, target.SelectedContent);
+            var item = Assert.IsType<TabItem>(target.Items[1]);
+            Assert.Same(item, target.SelectedItem);
+            Assert.Equal(item.Content, target.SelectedContent);
 
-            collection.RemoveAt(1);
+            target.Items.RemoveAt(1);
 
-            Assert.Same(collection[0], target.SelectedItem);
-            Assert.Equal(collection[0].Content, target.SelectedContent);
+            item = Assert.IsType<TabItem>(target.Items[0]);
+            Assert.Same(item, target.SelectedItem);
+            Assert.Equal(item.Content, target.SelectedContent);
         }
 
         [Fact]
         public void Removal_Should_Set_New_Item0_When_Item0_Selected()
         {
-            var collection = new ObservableCollection<TabItem>()
-            {
-                new TabItem
-                {
-                    Name = "first",
-                    Content = "foo",
-                },
-                new TabItem
-                {
-                    Name = "second",
-                    Content = "bar",
-                },
-                new TabItem
-                {
-                    Name = "3rd",
-                    Content = "barf",
-                },
-            };
-
             var target = new TabControl
             {
                 Template = TabControlTemplate(),
-                Items = collection,
+                Items =
+                {
+                    new TabItem
+                    {
+                        Name = "first",
+                        Content = "foo",
+                    },
+                    new TabItem
+                    {
+                        Name = "second",
+                        Content = "bar",
+                    },
+                    new TabItem
+                    {
+                        Name = "3rd",
+                        Content = "barf",
+                    },
+                }
             };
 
             Prepare(target);
-            target.SelectedItem = collection[0];
+            target.SelectedItem = target.Items[0];
 
-            Assert.Same(collection[0], target.SelectedItem);
-            Assert.Equal(collection[0].Content, target.SelectedContent);
+            var item = Assert.IsType<TabItem>(target.Items[0]);
+            Assert.Same(item, target.SelectedItem);
+            Assert.Equal(item.Content, target.SelectedContent);
 
-            collection.RemoveAt(0);
+            target.Items.RemoveAt(0);
 
-            Assert.Same(collection[0], target.SelectedItem);
-            Assert.Equal(collection[0].Content, target.SelectedContent);
+            item = Assert.IsType<TabItem>(target.Items[0]);
+            Assert.Same(item, target.SelectedItem);
+            Assert.Equal(item.Content, target.SelectedContent);
         }
 
         [Fact]
@@ -189,7 +183,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new TabControl
             {
                 Template = TabControlTemplate(),
-                Items = collection,
+                ItemsSource = collection,
             };
 
             Prepare(target);
@@ -207,26 +201,8 @@ namespace Avalonia.Controls.UnitTests
         [Fact]
         public void TabItem_Templates_Should_Be_Set_Before_TabItem_ApplyTemplate()
         {
-            var collection = new[]
-            {
-                new TabItem
-                {
-                    Name = "first",
-                    Content = "foo",
-                },
-                new TabItem
-                {
-                    Name = "second",
-                    Content = "bar",
-                },
-                new TabItem
-                {
-                    Name = "3rd",
-                    Content = "barf",
-                },
-            };
-
             var template = new FuncControlTemplate<TabItem>((x, __) => new Decorator());
+            TabControl target;
             var root = new TestRoot
             {
                 Styles =
@@ -239,13 +215,31 @@ namespace Avalonia.Controls.UnitTests
                         }
                     }
                 },
-                Child = new TabControl
+                Child = (target = new TabControl
                 {
                     Template = TabControlTemplate(),
-                    Items = collection,
-                }
+                    Items = 
+                    {
+                        new TabItem
+                        {
+                            Name = "first",
+                            Content = "foo",
+                        },
+                        new TabItem
+                        {
+                            Name = "second",
+                            Content = "bar",
+                        },
+                        new TabItem
+                        {
+                            Name = "3rd",
+                            Content = "barf",
+                        },
+                    },
+                })
             };
 
+            var collection = target.Items.Cast<TabItem>().ToList();
             Assert.Same(collection[0].Template, template);
             Assert.Same(collection[1].Template, template);
             Assert.Same(collection[2].Template, template);
@@ -271,7 +265,7 @@ namespace Avalonia.Controls.UnitTests
                 {
                     new FuncDataTemplate<Item>((x, __) => new Button { Content = x })
                 },
-                Items = items,
+                ItemsSource = items,
             };
 
             ApplyTemplate(target);
@@ -313,16 +307,14 @@ namespace Avalonia.Controls.UnitTests
         [Fact]
         public void Non_IHeadered_Control_Items_Should_Be_Ignored()
         {
-            var items = new[]
-            {
-                new TextBlock { Text = "foo" },
-                new TextBlock { Text = "bar" },
-            };
-
             var target = new TabControl
             {
                 Template = TabControlTemplate(),
-                Items = items,
+                Items =
+                {
+                    new TextBlock { Text = "foo" },
+                    new TextBlock { Text = "bar" },
+                },
             };
 
             ApplyTemplate(target);
@@ -343,7 +335,7 @@ namespace Avalonia.Controls.UnitTests
             TabControl target = new TabControl
             {
                 Template = TabControlTemplate(),
-                Items = new[]
+                Items =
                 {
                     new TabItem { Header = "Foo" },
                     new TabItem { Header = "Foo", Content = new Decorator() },
@@ -368,7 +360,7 @@ namespace Avalonia.Controls.UnitTests
                 Template = TabControlTemplate(),
                 ContentTemplate = new FuncDataTemplate<string>((x, _) =>
                     new TextBlock { Tag = "bar", Text = x }),
-                Items = new[] { "Foo" },
+                ItemsSource = new[] { "Foo" },
             };
             var root = new TestRoot(target);
 
@@ -392,7 +384,7 @@ namespace Avalonia.Controls.UnitTests
             {
                 Template = TabControlTemplate(),
                 DataContext = dataContext,
-                Items = new AvaloniaList<object> { tabItem }
+                Items = { tabItem }
             };
 
             ApplyTemplate(target);
@@ -409,7 +401,7 @@ namespace Avalonia.Controls.UnitTests
 <Window xmlns='https://github.com/avaloniaui'
         xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'
         xmlns:local='clr-namespace:Avalonia.Markup.Xaml.UnitTests.Xaml;assembly=Avalonia.Markup.Xaml.UnitTests'>
-    <TabControl Name='tabs' Items='{Binding Tabs}'/>
+    <TabControl Name='tabs' ItemsSource='{Binding Tabs}'/>
 </Window>";
                 var window = (Window)AvaloniaRuntimeXamlLoader.Load(xaml);
                 var tabControl = window.FindControl<TabControl>("tabs");
@@ -417,7 +409,7 @@ namespace Avalonia.Controls.UnitTests
                 tabControl.DataContext = new { Tabs = new List<string>() };
                 window.ApplyTemplate();
 
-                Assert.Equal(0, tabControl.Items.Count());
+                Assert.Equal(0, tabControl.ItemsSource.Count());
             }
         }
 
diff --git a/tests/Avalonia.Controls.UnitTests/TextBlockTests.cs b/tests/Avalonia.Controls.UnitTests/TextBlockTests.cs
index de5e5a8ea3..d8da198f5b 100644
--- a/tests/Avalonia.Controls.UnitTests/TextBlockTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/TextBlockTests.cs
@@ -192,7 +192,7 @@ namespace Avalonia.Controls.UnitTests
 
                 target.Inlines.Add(new Run("Hello World"));
 
-                Assert.Equal("Hello World", target.Text);
+                Assert.Equal(null, target.Text);
 
                 Assert.Equal(1, target.Inlines.Count);
 
diff --git a/tests/Avalonia.Controls.UnitTests/TreeViewTests.cs b/tests/Avalonia.Controls.UnitTests/TreeViewTests.cs
index eee6e49617..4f533c2f78 100644
--- a/tests/Avalonia.Controls.UnitTests/TreeViewTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/TreeViewTests.cs
@@ -31,7 +31,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new TreeView
             {
                 Template = CreateTreeViewTemplate(),
-                Items = CreateTestTreeData(),
+                ItemsSource = CreateTestTreeData(),
             };
 
             var root = new TestRoot(target);
@@ -54,7 +54,7 @@ namespace Avalonia.Controls.UnitTests
                 Child = target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = CreateTestTreeData(),
+                    ItemsSource = CreateTestTreeData(),
                     ItemTemplate = new FuncTreeDataTemplate<Node>(
                         (_, __) => new Canvas(),
                         x => x.Children),
@@ -82,7 +82,7 @@ namespace Avalonia.Controls.UnitTests
                 Child = target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = CreateTestTreeData(),
+                    ItemsSource = CreateTestTreeData(),
                     ItemContainerTheme = theme,
                     ItemTemplate = new FuncTreeDataTemplate<Node>(
                         (_, __) => new Canvas(),
@@ -112,7 +112,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new TreeView
             {
                 Template = CreateTreeViewTemplate(),
-                Items = CreateTestTreeData(),
+                ItemsSource = CreateTestTreeData(),
             };
 
             var root = new TestRoot(target);
@@ -131,7 +131,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new TreeView
             {
                 Template = CreateTreeViewTemplate(),
-                Items = CreateTestTreeData(),
+                ItemsSource = CreateTestTreeData(),
             };
 
             var root = new TestRoot(target);
@@ -151,7 +151,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new TreeView
             {
                 Template = CreateTreeViewTemplate(),
-                Items = tree,
+                ItemsSource = tree,
             };
 
             // For TreeViewItem to find its parent TreeView, OnAttachedToLogicalTree needs
@@ -181,7 +181,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                 };
 
                 var visualRoot = new TestRoot();
@@ -212,7 +212,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree
+                    ItemsSource = tree
                 };
 
                 var visualRoot = new TestRoot();
@@ -247,7 +247,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree
+                    ItemsSource = tree
                 };
 
                 var visualRoot = new TestRoot();
@@ -287,7 +287,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                     SelectionMode = SelectionMode.Multiple
                 };
 
@@ -330,7 +330,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                     SelectionMode = SelectionMode.Multiple
                 };
 
@@ -367,7 +367,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                     SelectionMode = SelectionMode.Multiple
                 };
 
@@ -404,7 +404,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                     SelectionMode = SelectionMode.Multiple
                 };
 
@@ -455,7 +455,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                 };
 
                 var visualRoot = new TestRoot();
@@ -488,7 +488,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                 };
 
                 var visualRoot = new TestRoot();
@@ -521,7 +521,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                 };
 
                 var visualRoot = new TestRoot();
@@ -554,7 +554,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                 };
 
                 var visualRoot = new TestRoot();
@@ -591,7 +591,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                 };
 
                 var visualRoot = new TestRoot();
@@ -649,7 +649,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                 };
 
                 var visualRoot = new TestRoot();
@@ -686,7 +686,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                 };
 
                 var visualRoot = new TestRoot();
@@ -744,7 +744,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                 };
 
                 var visualRoot = new TestRoot();
@@ -781,7 +781,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                 };
 
                 var visualRoot = new TestRoot();
@@ -839,7 +839,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                 };
 
                 var visualRoot = new TestRoot();
@@ -876,7 +876,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                 };
 
                 var visualRoot = new TestRoot();
@@ -934,7 +934,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                 };
 
                 var visualRoot = new TestRoot();
@@ -985,7 +985,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                 };
 
                 var visualRoot = new TestRoot();
@@ -1036,7 +1036,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                 };
 
                 var visualRoot = new TestRoot();
@@ -1066,7 +1066,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                 };
 
                 var visualRoot = new TestRoot();
@@ -1105,7 +1105,7 @@ namespace Avalonia.Controls.UnitTests
                     DataContext = dataContext
                 };
 
-                target.Bind(TreeView.ItemsProperty, new Binding("Items"));
+                target.Bind(TreeView.ItemsSourceProperty, new Binding("Items"));
                 target.Bind(TreeView.SelectedItemProperty, new Binding("SelectedItem"));
 
                 var visualRoot = new TestRoot();
@@ -1137,7 +1137,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new TreeView
             {
                 Template = CreateTreeViewTemplate(),
-                Items = new[] { "Foo", "Bar", "Baz " },
+                ItemsSource = new[] { "Foo", "Bar", "Baz " },
             };
 
             ApplyTemplates(target);
@@ -1171,7 +1171,7 @@ namespace Avalonia.Controls.UnitTests
                 {
                     new FuncDataTemplate<Node>((x, _) => new Button { Content = x })
                 },
-                Items = items,
+                ItemsSource = items,
             };
 
             ApplyTemplates(target);
@@ -1189,15 +1189,13 @@ namespace Avalonia.Controls.UnitTests
         [Fact]
         public void Control_Item_Should_Not_Be_NameScope()
         {
-            var items = new object[]
-            {
-                new TreeViewItem(),
-            };
-
             var target = new TreeView
             {
                 Template = CreateTreeViewTemplate(),
-                Items = items,
+                Items =
+                {
+                    new TreeViewItem(),
+                }
             };
 
             target.ApplyTemplate();
@@ -1215,7 +1213,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new TreeView
             {
                 Template = CreateTreeViewTemplate(),
-                Items = data,
+                ItemsSource = data,
             };
 
             var root = new TestRoot(target);
@@ -1256,7 +1254,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = data,
+                    ItemsSource = data,
                 };
 
                 var button = new Button();
@@ -1302,7 +1300,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = data,
+                    ItemsSource = data,
                     SelectedItem = selectedNode
                 };
 
@@ -1341,7 +1339,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                     SelectionMode = SelectionMode.Multiple
                 };
 
@@ -1379,7 +1377,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                     SelectionMode = SelectionMode.Multiple
                 };
 
@@ -1426,7 +1424,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                     SelectionMode = SelectionMode.Multiple
                 };
 
@@ -1473,7 +1471,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                     SelectionMode = SelectionMode.Multiple,
                 };
                 AvaloniaLocator.CurrentMutable.Bind<PlatformHotkeyConfiguration>().ToConstant(new Mock<PlatformHotkeyConfiguration>().Object);
@@ -1503,7 +1501,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                     SelectionMode = SelectionMode.Multiple,
                 };
 
@@ -1542,7 +1540,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                     SelectionMode = SelectionMode.Multiple,
                 };
 
@@ -1575,7 +1573,7 @@ namespace Avalonia.Controls.UnitTests
                 var target = new TreeView
                 {
                     Template = CreateTreeViewTemplate(),
-                    Items = tree,
+                    ItemsSource = tree,
                     SelectionMode = SelectionMode.Multiple,
                 };
 
@@ -1606,7 +1604,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new TreeView
             {
                 Template = CreateTreeViewTemplate(),
-                Items = tree,
+                ItemsSource = tree,
             };
 
             var visualRoot = new TestRoot();
@@ -1630,7 +1628,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new DerivedTreeView
             {
                 Template = CreateTreeViewTemplate(),
-                Items = tree,
+                ItemsSource = tree,
             };
 
             var visualRoot = new TestRoot();
@@ -1655,7 +1653,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new TreeView
             {
                 Template = CreateTreeViewTemplate(),
-                Items = tree,
+                ItemsSource = tree,
             };
 
             var visualRoot = new TestRoot();
@@ -1688,11 +1686,11 @@ namespace Avalonia.Controls.UnitTests
                 {
                     Template = CreateTreeViewTemplate(),
                     SelectionMode = SelectionMode.Multiple,
-                    Items = new List<Node>
-                {
-                    new Node { Value = "Root1", },
-                    new Node { Value = "Root2", },
-                },
+                    ItemsSource = new List<Node>
+                    {
+                        new Node { Value = "Root1", },
+                        new Node { Value = "Root2", },
+                    },
                 };
 
                 var visualRoot = new TestRoot
@@ -1726,7 +1724,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new TreeView
             {
                 Template = CreateTreeViewTemplate(),
-                Items = tree,
+                ItemsSource = tree,
             };
 
             var root = new TestRoot();
@@ -1760,7 +1758,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new TreeView
             {
                 Template = CreateTreeViewTemplate(),
-                Items = tree,
+                ItemsSource = tree,
             };
 
             var root = new TestRoot();
@@ -1788,7 +1786,7 @@ namespace Avalonia.Controls.UnitTests
             var target = new DerivedTreeViewWithDerivedTreeViewItems
             {
                 Template = CreateTreeViewTemplate(),
-                Items = tree,
+                ItemsSource = tree,
             };
 
             ApplyTemplates(target);
@@ -1825,14 +1823,14 @@ namespace Avalonia.Controls.UnitTests
 
             foreach (var index in indexes)
             {
-                var item = ((IList)c.Items)[index];
+                var item = c.ItemsView[index];
                 c = (ItemsControl)target.TreeContainerFromItem(item);
             }
 
             return (TreeViewItem)c;
         }
 
-        private IList<Node> CreateTestTreeData()
+        private AvaloniaList<Node> CreateTestTreeData()
         {
             return new AvaloniaList<Node>
             {
diff --git a/tests/Avalonia.Controls.UnitTests/Utils/HotKeyManagerTests.cs b/tests/Avalonia.Controls.UnitTests/Utils/HotKeyManagerTests.cs
index 336aad79da..75a1baad6e 100644
--- a/tests/Avalonia.Controls.UnitTests/Utils/HotKeyManagerTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/Utils/HotKeyManagerTests.cs
@@ -263,7 +263,7 @@ namespace Avalonia.Controls.UnitTests.Utils
             };
             var rootMenu = new Menu();
 
-            rootMenu.Items = new[] { menuitem };
+            rootMenu.Items.Add(menuitem);
 
             root.Content = rootMenu;
             return menuitem;
@@ -288,7 +288,7 @@ namespace Avalonia.Controls.UnitTests.Utils
             };
             var rootMenu = new Menu();
 
-            rootMenu.Items = new[] { menuitem };
+            rootMenu.Items.Add(menuitem);
 
             root.Content = rootMenu;
             return menuitem;
diff --git a/tests/Avalonia.Controls.UnitTests/VirtualizingCarouselPanelTests.cs b/tests/Avalonia.Controls.UnitTests/VirtualizingCarouselPanelTests.cs
index ea6b9367cf..721e8bde68 100644
--- a/tests/Avalonia.Controls.UnitTests/VirtualizingCarouselPanelTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/VirtualizingCarouselPanelTests.cs
@@ -218,7 +218,7 @@ namespace Avalonia.Controls.UnitTests
         {
             var carousel = new Carousel
             {
-                Items = items,
+                ItemsSource = items,
                 Template = CarouselTemplate(),
                 PageTransition = transition,
             };
diff --git a/tests/Avalonia.Controls.UnitTests/VirtualizingStackPanelTests.cs b/tests/Avalonia.Controls.UnitTests/VirtualizingStackPanelTests.cs
index ba8e7242a1..42b419bbcc 100644
--- a/tests/Avalonia.Controls.UnitTests/VirtualizingStackPanelTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/VirtualizingStackPanelTests.cs
@@ -9,15 +9,12 @@ using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Templates;
 using Avalonia.Data;
 using Avalonia.Layout;
-using Avalonia.LogicalTree;
 using Avalonia.Media;
 using Avalonia.Styling;
 using Avalonia.UnitTests;
 using Avalonia.VisualTree;
 using Xunit;
 
-#nullable enable
-
 namespace Avalonia.Controls.UnitTests
 {
     public class VirtualizingStackPanelTests
@@ -53,7 +50,7 @@ namespace Avalonia.Controls.UnitTests
 
             Assert.Empty(itemsControl.GetRealizedContainers());
 
-            itemsControl.Items = new[] { "foo", "bar" };
+            itemsControl.ItemsSource = new[] { "foo", "bar" };
             Layout(target);
 
             AssertRealizedItems(target, itemsControl, 0, 2);
@@ -99,7 +96,7 @@ namespace Avalonia.Controls.UnitTests
         {
             using var app = App();
             var (target, _, itemsControl) = CreateTarget();
-            var items = (IList)itemsControl.Items!;
+            var items = (IList)itemsControl.ItemsSource!;
 
             Assert.Equal(10, target.GetRealizedElements().Count);
 
@@ -131,7 +128,7 @@ namespace Avalonia.Controls.UnitTests
         {
             using var app = App();
             var (target, _, itemsControl) = CreateTarget();
-            var items = (IList)itemsControl.Items!;
+            var items = (IList)itemsControl.ItemsSource!;
 
             Assert.Equal(10, target.GetRealizedElements().Count);
 
@@ -161,7 +158,7 @@ namespace Avalonia.Controls.UnitTests
         {
             using var app = App();
             var (target, _, itemsControl) = CreateTarget();
-            var items = (ObservableCollection<string>)itemsControl.Items!;
+            var items = (ObservableCollection<string>)itemsControl.ItemsSource!;
 
             Assert.Equal(10, target.GetRealizedElements().Count);
 
@@ -190,7 +187,7 @@ namespace Avalonia.Controls.UnitTests
         {
             using var app = App();
             var (target, _, itemsControl) = CreateTarget();
-            var items = (ObservableCollection<string>)itemsControl.Items!;
+            var items = (ObservableCollection<string>)itemsControl.ItemsSource!;
 
             Assert.Equal(10, target.GetRealizedElements().Count);
 
@@ -409,6 +406,36 @@ namespace Avalonia.Controls.UnitTests
             }
         }
 
+        [Fact]
+        public void ContainerPrepared_Is_Raised_When_Scrolling()
+        {
+            using var app = App();
+            var (target, scroll, itemsControl) = CreateTarget();
+            var raised = 0;
+
+            itemsControl.ContainerPrepared += (s, e) => ++raised;
+
+            scroll.Offset = new Vector(0, 200);
+            Layout(target);
+
+            Assert.Equal(10, raised);
+        }
+
+        [Fact]
+        public void ContainerClearing_Is_Raised_When_Scrolling()
+        {
+            using var app = App();
+            var (target, scroll, itemsControl) = CreateTarget();
+            var raised = 0;
+
+            itemsControl.ContainerClearing += (s, e) => ++raised;
+
+            scroll.Offset = new Vector(0, 200);
+            Layout(target);
+
+            Assert.Equal(10, raised);
+        }
+
         private static IReadOnlyList<int> GetRealizedIndexes(VirtualizingStackPanel target, ItemsControl itemsControl)
         {
             return target.GetRealizedElements()
@@ -473,7 +500,7 @@ namespace Avalonia.Controls.UnitTests
 
             var itemsControl = new ItemsControl
             {
-                Items = items,
+                ItemsSource = items,
                 Template = new FuncControlTemplate<ItemsControl>((_, _) => scroll),
                 ItemsPanel = new FuncTemplate<Panel>(() => target),
             };
diff --git a/tests/Avalonia.IntegrationTests.Appium/ElementExtensions.cs b/tests/Avalonia.IntegrationTests.Appium/ElementExtensions.cs
index 2184c5c155..99c30085d6 100644
--- a/tests/Avalonia.IntegrationTests.Appium/ElementExtensions.cs
+++ b/tests/Avalonia.IntegrationTests.Appium/ElementExtensions.cs
@@ -11,19 +11,26 @@ using Xunit;
 
 namespace Avalonia.IntegrationTests.Appium
 {
+    public record class WindowChrome(
+        AppiumWebElement? Close,
+        AppiumWebElement? Minimize,
+        AppiumWebElement? Maximize,
+        AppiumWebElement? FullScreen);
+
     internal static class ElementExtensions
     {
         public static IReadOnlyList<AppiumWebElement> GetChildren(this AppiumWebElement element) =>
             element.FindElementsByXPath("*/*");
 
-        public static (AppiumWebElement close, AppiumWebElement minimize, AppiumWebElement maximize) GetChromeButtons(this AppiumWebElement window)
+        public static WindowChrome GetChromeButtons(this AppiumWebElement window)
         {
             if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
             {
-                var closeButton = window.FindElementByXPath("//XCUIElementTypeButton[1]");
-                var fullscreenButton = window.FindElementByXPath("//XCUIElementTypeButton[2]");
-                var minimizeButton = window.FindElementByXPath("//XCUIElementTypeButton[3]");
-                return (closeButton, minimizeButton, fullscreenButton);
+                var closeButton = window.FindElementsByAccessibilityId("_XCUI:CloseWindow").FirstOrDefault();
+                var fullscreenButton = window.FindElementsByAccessibilityId("_XCUI:FullScreenWindow").FirstOrDefault();
+                var minimizeButton = window.FindElementsByAccessibilityId("_XCUI:MinimizeWindow").FirstOrDefault();
+                var zoomButton = window.FindElementsByAccessibilityId("_XCUI:ZoomWindow").FirstOrDefault();
+                return new(closeButton, minimizeButton, zoomButton, fullscreenButton);
             }
 
             throw new NotSupportedException("GetChromeButtons not supported on this platform.");
@@ -138,7 +145,7 @@ namespace Avalonia.IntegrationTests.Appium
                     var text = windows.Select(x => x.Text).ToList();
                     var newWindow = session.FindElements(By.XPath("/XCUIElementTypeApplication/XCUIElementTypeWindow"))
                         .First(x => x.Text == newWindowTitle);
-                    var (close, _, _) = ((AppiumWebElement)newWindow).GetChromeButtons();
+                    var close = ((AppiumWebElement)newWindow).FindElementByAccessibilityId("_XCUI:CloseWindow");
                     close!.Click();
                     Thread.Sleep(1000);
                 });
diff --git a/tests/Avalonia.IntegrationTests.Appium/PlatformFactAttribute.cs b/tests/Avalonia.IntegrationTests.Appium/PlatformFactAttribute.cs
index 3acf9fd5e2..17c42216e9 100644
--- a/tests/Avalonia.IntegrationTests.Appium/PlatformFactAttribute.cs
+++ b/tests/Avalonia.IntegrationTests.Appium/PlatformFactAttribute.cs
@@ -17,6 +17,7 @@ namespace Avalonia
     internal class PlatformFactAttribute : FactAttribute
     {
         private readonly string? _reason;
+        private string? _skip;
 
         public PlatformFactAttribute(TestPlatforms platforms, string? reason = null)
         {
@@ -28,8 +29,16 @@ namespace Avalonia
 
         public override string? Skip
         {
-            get => IsSupported() ? null : $"Ignored on {RuntimeInformation.OSDescription}" + (_reason is not null ? $" reason: \"{_reason}\"" : "");
-            set => throw new NotSupportedException();
+            get
+            {
+                if (_skip is not null)
+                    return _skip;
+                if (!IsSupported())
+                    return $"Ignored on {RuntimeInformation.OSDescription}" +
+                           (_reason is not null ? $" reason: '{_reason}'" : "");
+                return null;
+            }
+            set => _skip = value;
         }
 
         private bool IsSupported()
diff --git a/tests/Avalonia.IntegrationTests.Appium/PlatformTheoryAttribute.cs b/tests/Avalonia.IntegrationTests.Appium/PlatformTheoryAttribute.cs
index 7ac30ee11b..46a8e1af98 100644
--- a/tests/Avalonia.IntegrationTests.Appium/PlatformTheoryAttribute.cs
+++ b/tests/Avalonia.IntegrationTests.Appium/PlatformTheoryAttribute.cs
@@ -7,14 +7,21 @@ namespace Avalonia.IntegrationTests.Appium
 {
     internal class PlatformTheoryAttribute : TheoryAttribute
     {
+        private string? _skip;
+
         public PlatformTheoryAttribute(TestPlatforms platforms = TestPlatforms.All) => Platforms = platforms;
 
         public TestPlatforms Platforms { get; }
 
         public override string? Skip
         {
-            get => IsSupported() ? null : $"Ignored on {RuntimeInformation.OSDescription}";
-            set => throw new NotSupportedException();
+            get
+            {
+                if (_skip is not null)
+                    return _skip;
+                return !IsSupported() ? $"Ignored on {RuntimeInformation.OSDescription}" : null;
+            }
+            set => _skip = value;
         }
 
         private bool IsSupported()
diff --git a/tests/Avalonia.IntegrationTests.Appium/WindowTests_MacOS.cs b/tests/Avalonia.IntegrationTests.Appium/WindowTests_MacOS.cs
index 039d30bbc1..68a31c7ccb 100644
--- a/tests/Avalonia.IntegrationTests.Appium/WindowTests_MacOS.cs
+++ b/tests/Avalonia.IntegrationTests.Appium/WindowTests_MacOS.cs
@@ -83,9 +83,9 @@ namespace Avalonia.IntegrationTests.Appium
         public void WindowOrder_Modal_Dialog_Stays_InFront_Of_Parent_When_In_Fullscreen()
         {
             var mainWindow = GetWindow("MainWindow");
-            var buttons = mainWindow.GetChromeButtons();
+            var fullScreen = mainWindow.FindElementByAccessibilityId("_XCUI:FullScreenWindow");
 
-            buttons.maximize.Click();
+            fullScreen.Click();
 
             Thread.Sleep(500);
 
@@ -239,17 +239,18 @@ namespace Avalonia.IntegrationTests.Appium
         public void Parent_Window_Has_Disabled_ChromeButtons_When_Modal_Dialog_Shown()
         {
             var window = GetWindow("MainWindow");
-            var (closeButton, miniaturizeButton, zoomButton) = window.GetChromeButtons();
+            var windowChrome = window.GetChromeButtons();
 
-            Assert.True(closeButton.Enabled);
-            Assert.True(zoomButton.Enabled);
-            Assert.True(miniaturizeButton.Enabled);
+            Assert.True(windowChrome.Close!.Enabled);
+            Assert.True(windowChrome.FullScreen!.Enabled);
+            Assert.True(windowChrome.Minimize!.Enabled);
+            Assert.Null(windowChrome.Maximize);
 
             using (OpenWindow(new PixelSize(200, 100), ShowWindowMode.Modal, WindowStartupLocation.CenterOwner))
             {
-                Assert.False(closeButton.Enabled);
-                Assert.False(zoomButton.Enabled);
-                Assert.False(miniaturizeButton.Enabled);
+                Assert.False(windowChrome.Close!.Enabled);
+                Assert.False(windowChrome.FullScreen!.Enabled);
+                Assert.False(windowChrome.Minimize!.Enabled);
             }
         }
 
@@ -259,11 +260,11 @@ namespace Avalonia.IntegrationTests.Appium
             using (OpenWindow(new PixelSize(200, 100), ShowWindowMode.Modal, WindowStartupLocation.CenterOwner))
             {
                 var secondaryWindow = GetWindow("SecondaryWindow");
-                var (closeButton, miniaturizeButton, zoomButton) = secondaryWindow.GetChromeButtons();
+                var windowChrome = secondaryWindow.GetChromeButtons();
 
-                Assert.True(closeButton.Enabled);
-                Assert.True(zoomButton.Enabled);
-                Assert.False(miniaturizeButton.Enabled);
+                Assert.True(windowChrome.Close!.Enabled);
+                Assert.True(windowChrome.Maximize!.Enabled);
+                Assert.False(windowChrome.Minimize!.Enabled);
             }
         }
         
@@ -274,7 +275,7 @@ namespace Avalonia.IntegrationTests.Appium
             using (OpenWindow(new PixelSize(200, 100), mode, WindowStartupLocation.Manual))
             {
                 var secondaryWindow = GetWindow("SecondaryWindow");
-                var (_, miniaturizeButton, _) = secondaryWindow.GetChromeButtons();
+                var miniaturizeButton = secondaryWindow.FindElementByAccessibilityId("_XCUI:MinimizeWindow");
 
                 Assert.False(miniaturizeButton.Enabled);
             }
@@ -288,7 +289,7 @@ namespace Avalonia.IntegrationTests.Appium
             using (OpenWindow(new PixelSize(200, 100), mode, WindowStartupLocation.Manual))
             {
                 var secondaryWindow = GetWindow("SecondaryWindow");
-                var (_, miniaturizeButton, _) = secondaryWindow.GetChromeButtons();
+                var miniaturizeButton = secondaryWindow.FindElementByAccessibilityId("_XCUI:MinimizeWindow");
 
                 miniaturizeButton.Click();
                 Thread.Sleep(1000);
@@ -332,7 +333,7 @@ namespace Avalonia.IntegrationTests.Appium
 
             // Close the window manually.
             secondaryWindow = GetWindow("SecondaryWindow");
-            secondaryWindow.GetChromeButtons().close.Click();
+            secondaryWindow.FindElementByAccessibilityId("_XCUI:CloseWindow").Click();
         }
 
         [PlatformTheory(TestPlatforms.MacOS)]
@@ -344,22 +345,92 @@ namespace Avalonia.IntegrationTests.Appium
             using (OpenWindow(null, mode, WindowStartupLocation.Manual, canResize: false))
             {
                 var secondaryWindow = GetWindow("SecondaryWindow");
-                var (_, _, zoomButton) = secondaryWindow.GetChromeButtons();
+                var zoomButton = mode == ShowWindowMode.NonOwned ?
+                    secondaryWindow.FindElementByAccessibilityId("_XCUI:FullScreenWindow") :
+                    secondaryWindow.FindElementByAccessibilityId("_XCUI:ZoomWindow");
                 Assert.False(zoomButton.Enabled);
             }
         }
-        
+
+        [PlatformFact(TestPlatforms.MacOS)]
+        public void Toggling_SystemDecorations_Should_Preserve_ExtendClientArea()
+        {
+            // #10650
+            using (OpenWindow(extendClientArea: true))
+            {
+                var secondaryWindow = GetWindow("SecondaryWindow");
+                
+                // The XPath of the title bar text _should_ be "XCUIElementTypeStaticText"
+                // but Appium seems to put a fake node between the window and the title bar
+                // https://stackoverflow.com/a/71914227/6448
+                var titleBar = secondaryWindow.FindElementsByXPath("/*/XCUIElementTypeStaticText").Count;
+                
+                Assert.Equal(0, titleBar);
+
+                secondaryWindow.FindElementByAccessibilityId("CurrentSystemDecorations").Click();
+                _session.FindElementByAccessibilityId("SystemDecorationsNone").SendClick();
+                secondaryWindow.FindElementByAccessibilityId("CurrentSystemDecorations").Click();
+                _session.FindElementByAccessibilityId("SystemDecorationsFull").SendClick();
+
+                titleBar = secondaryWindow.FindElementsByXPath("/*/XCUIElementTypeStaticText").Count;
+                Assert.Equal(0, titleBar);
+            }
+        }
+
+        [PlatformTheory(TestPlatforms.MacOS)]
+        [InlineData(SystemDecorations.None)]
+        [InlineData(SystemDecorations.BorderOnly)]
+        [InlineData(SystemDecorations.Full)]
+        public void ExtendClientArea_SystemDecorations_Shows_Correct_Buttons(SystemDecorations decorations)
+        {
+            // #10650
+            using (OpenWindow(extendClientArea: true, systemDecorations: decorations))
+            {
+                var secondaryWindow = GetWindow("SecondaryWindow");
+
+                try
+                {
+                    var chrome = secondaryWindow.GetChromeButtons();
+                
+                    if (decorations == SystemDecorations.Full)
+                    {
+                        Assert.NotNull(chrome.Close);
+                        Assert.NotNull(chrome.Minimize);
+                        Assert.NotNull(chrome.FullScreen);
+                    }
+                    else
+                    {
+                        Assert.Null(chrome.Close);
+                        Assert.Null(chrome.Minimize);
+                        Assert.Null(chrome.FullScreen);
+                    }
+                }
+                finally
+                {
+                    if (decorations != SystemDecorations.Full)
+                    {
+                        secondaryWindow.FindElementByAccessibilityId("CurrentSystemDecorations").Click();
+                        _session.FindElementByAccessibilityId("SystemDecorationsFull").SendClick();
+                    }
+                }
+            }
+        }
+
         private IDisposable OpenWindow(
-            PixelSize? size,
-            ShowWindowMode mode,
-            WindowStartupLocation location,
-            bool canResize = true)
+            PixelSize? size = null,
+            ShowWindowMode mode = ShowWindowMode.NonOwned,
+            WindowStartupLocation location = WindowStartupLocation.Manual,
+            bool canResize = true,
+            SystemDecorations systemDecorations = SystemDecorations.Full,
+            bool extendClientArea = false)
         {
             var sizeTextBox = _session.FindElementByAccessibilityId("ShowWindowSize");
             var modeComboBox = _session.FindElementByAccessibilityId("ShowWindowMode");
             var locationComboBox = _session.FindElementByAccessibilityId("ShowWindowLocation");
             var canResizeCheckBox = _session.FindElementByAccessibilityId("ShowWindowCanResize");
             var showButton = _session.FindElementByAccessibilityId("ShowWindow");
+            var systemDecorationsComboBox = _session.FindElementByAccessibilityId("ShowWindowSystemDecorations");
+            var extendClientAreaCheckBox = _session.FindElementByAccessibilityId("ShowWindowExtendClientAreaToDecorationsHint");
 
             if (size.HasValue)
                 sizeTextBox.SendKeys($"{size.Value.Width}, {size.Value.Height}");
@@ -379,6 +450,15 @@ namespace Avalonia.IntegrationTests.Appium
             if (canResizeCheckBox.GetIsChecked() != canResize)
                 canResizeCheckBox.Click();
 
+            if (systemDecorationsComboBox.GetComboBoxValue() != systemDecorations.ToString())
+            {
+                systemDecorationsComboBox.Click();
+                _session.FindElementByName(systemDecorations.ToString()).SendClick();
+            }
+            
+            if (extendClientAreaCheckBox.GetIsChecked() != extendClientArea)
+                extendClientAreaCheckBox.Click();
+            
             return showButton.OpenWindowWithClick();
         }
 
diff --git a/tests/Avalonia.LeakTests/ControlTests.cs b/tests/Avalonia.LeakTests/ControlTests.cs
index c9f79871c9..1320d34f39 100644
--- a/tests/Avalonia.LeakTests/ControlTests.cs
+++ b/tests/Avalonia.LeakTests/ControlTests.cs
@@ -353,7 +353,7 @@ namespace Avalonia.LeakTests
                                     (x, _) => new TextBlock { Text = x.Name },
                                     x => x.Children)
                             },
-                            Items = nodes
+                            ItemsSource = nodes
                         }
                     };
 
@@ -428,7 +428,7 @@ namespace Avalonia.LeakTests
                     {
                         Content = new TabControl
                         {
-                            Items = new[] { new TabItem() }
+                            ItemsSource = new[] { new TabItem() }
                         }
                     };
 
@@ -440,7 +440,7 @@ namespace Avalonia.LeakTests
                     Assert.IsType<TabItem>(tabControl.Presenter.Panel.Children[0]);
 
                     // Clear the items and ensure the TabItem is removed.
-                    tabControl.Items = null;
+                    tabControl.ItemsSource = null;
                     window.LayoutManager.ExecuteLayoutPass();
                     Assert.Empty(tabControl.Presenter.Panel.Children);
 
@@ -545,7 +545,7 @@ namespace Avalonia.LeakTests
                 {
                     var contextMenu = new ContextMenu
                     {
-                        Items = new[]
+                        Items =
                         {
                             new MenuItem { Header = "Foo" },
                             new MenuItem { Header = "Foo" },
@@ -594,7 +594,7 @@ namespace Avalonia.LeakTests
                 {
                     var contextMenu = new ContextMenu
                     {
-                        Items = new[]
+                        Items =
                         {
                             new MenuItem { Header = "Foo" },
                             new MenuItem { Header = "Foo" },
@@ -740,7 +740,7 @@ namespace Avalonia.LeakTests
                             }),
                             (lb = new ListBox
                             {
-                                Items = items,
+                                ItemsSource = items,
                                 ItemTemplate = new FuncDataTemplate<int>((_, _) =>
                                     new Canvas
                                     {
@@ -858,7 +858,7 @@ namespace Avalonia.LeakTests
                     // Add the listbox and render it
                     tl.Content = listBox;
                     lm.ExecuteInitialLayoutPass();
-                    listBox.Items = keyGestures;
+                    listBox.ItemsSource = keyGestures;
                     lm.ExecuteLayoutPass();
 
                     // Let the button detach when clearing the source items
diff --git a/tests/Avalonia.Markup.UnitTests/Data/MultiBindingTests.cs b/tests/Avalonia.Markup.UnitTests/Data/MultiBindingTests.cs
index bf9631760a..f6a4437a9e 100644
--- a/tests/Avalonia.Markup.UnitTests/Data/MultiBindingTests.cs
+++ b/tests/Avalonia.Markup.UnitTests/Data/MultiBindingTests.cs
@@ -173,11 +173,11 @@ namespace Avalonia.Markup.UnitTests.Data
                 },
             };
 
-            target.Bind(ItemsControl.ItemsProperty, binding);
+            target.Bind(ItemsControl.ItemsSourceProperty, binding);
             Assert.Equal(target.ItemCount, 3);
-            Assert.Equal(target.Items.ElementAt(0), source.A);
-            Assert.Equal(target.Items.ElementAt(1), source.B);
-            Assert.Equal(target.Items.ElementAt(2), source.C);
+            Assert.Equal(target.ItemsView[0], source.A);
+            Assert.Equal(target.ItemsView[1], source.B);
+            Assert.Equal(target.ItemsView[2], source.C);
         }
 
         private class ConcatConverter : IMultiValueConverter
diff --git a/tests/Avalonia.Markup.Xaml.UnitTests/MarkupExtensions/CompiledBindingExtensionTests.cs b/tests/Avalonia.Markup.Xaml.UnitTests/MarkupExtensions/CompiledBindingExtensionTests.cs
index 27634b457b..57d6a8902a 100644
--- a/tests/Avalonia.Markup.Xaml.UnitTests/MarkupExtensions/CompiledBindingExtensionTests.cs
+++ b/tests/Avalonia.Markup.Xaml.UnitTests/MarkupExtensions/CompiledBindingExtensionTests.cs
@@ -122,7 +122,7 @@ namespace Avalonia.Markup.Xaml.UnitTests.MarkupExtensions
         xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'
         xmlns:local='clr-namespace:Avalonia.Markup.Xaml.UnitTests.MarkupExtensions;assembly=Avalonia.Markup.Xaml.UnitTests'
         x:DataType='local:TestDataContext'>
-    <ItemsControl Name='itemsControl' Items='{CompiledBinding Path=ListProperty}'>
+    <ItemsControl Name='itemsControl' ItemsSource='{CompiledBinding Path=ListProperty}'>
 	    <ItemsControl.ItemTemplate>
 		    <DataTemplate>
 			    <TextBlock />
@@ -143,7 +143,7 @@ namespace Avalonia.Markup.Xaml.UnitTests.MarkupExtensions
 
                 window.DataContext = dataContext;
 
-                Assert.Equal(dataContext.ListProperty, textBlock.Items);
+                Assert.Equal(dataContext.ListProperty, textBlock.ItemsSource);
             }
         }
         
@@ -528,7 +528,7 @@ namespace Avalonia.Markup.Xaml.UnitTests.MarkupExtensions
         xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'
         xmlns:local='clr-namespace:Avalonia.Markup.Xaml.UnitTests.MarkupExtensions;assembly=Avalonia.Markup.Xaml.UnitTests'
         x:DataType='local:TestDataContext'>
-    <ItemsControl Items='{CompiledBinding ListProperty}' Name='target'>
+    <ItemsControl ItemsSource='{CompiledBinding ListProperty}' Name='target'>
         <ItemsControl.ItemTemplate>
             <DataTemplate>
                 <TextBlock Text='{CompiledBinding}' Name='textBlock' />
@@ -1782,7 +1782,7 @@ namespace Avalonia.Markup.Xaml.UnitTests.MarkupExtensions
         xmlns:local='clr-namespace:Avalonia.Markup.Xaml.UnitTests.MarkupExtensions;assembly=Avalonia.Markup.Xaml.UnitTests'
         x:DataType='local:TestDataContext'
         x:CompileBindings='True'>
-    <ComboBox x:Name='comboBox' Items='{Binding GenericProperty}' SelectedItem='{Binding GenericProperty.CurrentItem}' />
+    <ComboBox x:Name='comboBox' ItemsSource='{Binding GenericProperty}' SelectedItem='{Binding GenericProperty.CurrentItem}' />
 </Window>";
                 var window = (Window)AvaloniaRuntimeXamlLoader.Load(xaml);
                 var comboBox = window.FindControl<ComboBox>("comboBox");
@@ -1991,7 +1991,10 @@ namespace Avalonia.Markup.Xaml.UnitTests.MarkupExtensions
     public class DataGridLikeControl : Control
     {
         public static readonly DirectProperty<DataGridLikeControl, IEnumerable?> ItemsProperty =
-            ItemsControl.ItemsProperty.AddOwner<DataGridLikeControl>(o => o.Items, (o, v) => o.Items = v);
+            AvaloniaProperty.RegisterDirect<DataGridLikeControl, IEnumerable?>(
+                nameof(Items),
+                x => x.Items,
+                (x, v) => x.Items = v);
 
         private IEnumerable _items;
         public IEnumerable Items
diff --git a/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/BasicTests.cs b/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/BasicTests.cs
index 1b795a304c..5d55c831a3 100644
--- a/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/BasicTests.cs
+++ b/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/BasicTests.cs
@@ -505,7 +505,7 @@ namespace Avalonia.Markup.Xaml.UnitTests.Xaml
             {
                 var xaml = @"
 <Window xmlns='https://github.com/avaloniaui'>
-    <ItemsControl Name='itemsControl' Items='{Binding}'>
+    <ItemsControl Name='itemsControl' ItemsSource='{Binding}'>
     </ItemsControl>
 </Window>
 ";
@@ -522,7 +522,7 @@ namespace Avalonia.Markup.Xaml.UnitTests.Xaml
 
                 target.DataContext = items;
 
-                Assert.Equal(items, itemsControl.Items);
+                Assert.Equal(items, itemsControl.ItemsSource);
             }
         }
 
@@ -760,7 +760,7 @@ namespace Avalonia.Markup.Xaml.UnitTests.Xaml
             {
                 var xaml = @"
 <Window xmlns='https://github.com/avaloniaui'>
-    <ListBox Items='{Binding Items}' SelectedItems='{Binding SelectedItems}'/>
+    <ListBox ItemsSource='{Binding Items}' SelectedItems='{Binding SelectedItems}'/>
 </Window>";
 
                 var window = AvaloniaRuntimeXamlLoader.Parse<Window>(xaml);
@@ -773,7 +773,7 @@ namespace Avalonia.Markup.Xaml.UnitTests.Xaml
 
                 window.DataContext = vm;
 
-                Assert.Equal(vm.Items, listBox.Items);
+                Assert.Equal(vm.Items, listBox.ItemsSource);
 
                 Assert.Equal(vm.SelectedItems, listBox.SelectedItems);
             }
diff --git a/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/DataTemplateTests.cs b/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/DataTemplateTests.cs
index 70146bb0c1..05e81dc0ba 100644
--- a/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/DataTemplateTests.cs
+++ b/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/DataTemplateTests.cs
@@ -74,7 +74,7 @@ namespace Avalonia.Markup.Xaml.UnitTests.Xaml
 <Window xmlns='https://github.com/avaloniaui'
         xmlns:sys='clr-namespace:System;assembly=mscorlib'
         xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'>
-    <ItemsControl Name='itemsControl' Items='{Binding}'>
+    <ItemsControl Name='itemsControl' ItemsSource='{Binding}'>
         <ItemsControl.ItemTemplate>
             <DataTemplate>
                 <UserControl Name='foo'/>
diff --git a/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/StyleTests.cs b/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/StyleTests.cs
index 933958b3a0..114b9d6064 100644
--- a/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/StyleTests.cs
+++ b/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/StyleTests.cs
@@ -377,7 +377,7 @@ namespace Avalonia.Markup.Xaml.UnitTests.Xaml
                 };
 
                 var list = window.FindControl<ListBox>("list");
-                list.Items = collection;
+                list.ItemsSource = collection;
 
                 window.Show();
 
diff --git a/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/XamlIlTests.cs b/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/XamlIlTests.cs
index 09ed78accb..3154da8ecf 100644
--- a/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/XamlIlTests.cs
+++ b/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/XamlIlTests.cs
@@ -391,7 +391,7 @@ namespace Avalonia.Markup.Xaml.UnitTests
   </ItemsControl>
 </Window>
 ", typeof(XamlIlBugTestsEventHandlerCodeBehind).Assembly, this);
-            ((ItemsControl)Content).Items = new[] {"123"};
+            ((ItemsControl)Content).ItemsSource = new[] {"123"};
         }
     }
     
diff --git a/tests/Avalonia.ReactiveUI.UnitTests/AutoDataTemplateBindingHookTest.cs b/tests/Avalonia.ReactiveUI.UnitTests/AutoDataTemplateBindingHookTest.cs
index c00303f4f8..9f49d94801 100644
--- a/tests/Avalonia.ReactiveUI.UnitTests/AutoDataTemplateBindingHookTest.cs
+++ b/tests/Avalonia.ReactiveUI.UnitTests/AutoDataTemplateBindingHookTest.cs
@@ -41,7 +41,7 @@ namespace Avalonia.ReactiveUI.UnitTests
                 
                 Content = List;
                 ViewModel = new ExampleViewModel();
-                this.OneWayBind(ViewModel, x => x.Items, x => x.List.Items);
+                this.OneWayBind(ViewModel, x => x.Items, x => x.List.ItemsSource);
             }
         }
 
diff --git a/tests/Avalonia.RenderTests/Controls/CustomRenderTests.cs b/tests/Avalonia.RenderTests/Controls/CustomRenderTests.cs
index 1199184d14..7a2c60baf4 100644
--- a/tests/Avalonia.RenderTests/Controls/CustomRenderTests.cs
+++ b/tests/Avalonia.RenderTests/Controls/CustomRenderTests.cs
@@ -88,7 +88,7 @@ namespace Avalonia.Direct2D1.RenderTests.Controls
                 Height = 200,
                 Child = new CustomRenderer((control, context) =>
                 {
-                    using (var transform = context.PushPreTransform(Matrix.CreateTranslation(100, 100)))
+                    using (var transform = context.PushTransform(Matrix.CreateTranslation(100, 100)))
                     using (var clip = context.PushClip(new Rect(0, 0, 100, 100)))
                     {
                         context.FillRectangle(Brushes.Blue, new Rect(0, 0, 200, 200));
@@ -112,7 +112,7 @@ namespace Avalonia.Direct2D1.RenderTests.Controls
                 Height = 200,
                 Child = new CustomRenderer((control, context) =>
                 {
-                    using (var transform = context.PushPreTransform(Matrix.CreateTranslation(100, 100)))
+                    using (var transform = context.PushTransform(Matrix.CreateTranslation(100, 100)))
                     using (var clip = context.PushClip(new Rect(0, 0, 100, 100)))
                     {
                         context.FillRectangle(Brushes.Blue, new Rect(0, 0, 200, 200));
diff --git a/tests/Avalonia.RenderTests/Media/ConicGradientBrushTests.cs b/tests/Avalonia.RenderTests/Media/ConicGradientBrushTests.cs
index ef400410a4..a6170f9e94 100644
--- a/tests/Avalonia.RenderTests/Media/ConicGradientBrushTests.cs
+++ b/tests/Avalonia.RenderTests/Media/ConicGradientBrushTests.cs
@@ -200,7 +200,7 @@ namespace Avalonia.Direct2D1.RenderTests.Media
                 Child = new DrawnControl(c =>
                 {
                     c.DrawRectangle(brush, null, new Rect(0, 0, 100, 100));
-                    using (c.PushPreTransform(Matrix.CreateTranslation(100, 100)))
+                    using (c.PushTransform(Matrix.CreateTranslation(100, 100)))
                         c.DrawRectangle(brush, null, new Rect(0, 0, 100, 100));
                 }),
             };
diff --git a/tests/Avalonia.RenderTests/Media/LinearGradientBrushTests.cs b/tests/Avalonia.RenderTests/Media/LinearGradientBrushTests.cs
index dd9d2f9b39..ac49b6d078 100644
--- a/tests/Avalonia.RenderTests/Media/LinearGradientBrushTests.cs
+++ b/tests/Avalonia.RenderTests/Media/LinearGradientBrushTests.cs
@@ -95,7 +95,7 @@ namespace Avalonia.Direct2D1.RenderTests.Media
                 {
                     c.DrawRectangle(brush, null, new Rect(0, 0, 100, 100));
 
-                    using (c.PushPreTransform(Matrix.CreateTranslation(100, 100)))
+                    using (c.PushTransform(Matrix.CreateTranslation(100, 100)))
                         c.DrawRectangle(brush, null, new Rect(0, 0, 100, 100));
                 }),
             };
diff --git a/tests/Avalonia.RenderTests/Media/RadialGradientBrushTests.cs b/tests/Avalonia.RenderTests/Media/RadialGradientBrushTests.cs
index e52f844359..78f1b5c23f 100644
--- a/tests/Avalonia.RenderTests/Media/RadialGradientBrushTests.cs
+++ b/tests/Avalonia.RenderTests/Media/RadialGradientBrushTests.cs
@@ -185,7 +185,7 @@ namespace Avalonia.Direct2D1.RenderTests.Media
                 Child = new DrawnControl(c =>
                 {
                     c.DrawRectangle(brush, null, new Rect(0, 0, 100, 100));
-                    using (c.PushPreTransform(Matrix.CreateTranslation(100, 100)))
+                    using (c.PushTransform(Matrix.CreateTranslation(100, 100)))
                         c.DrawRectangle(brush, null, new Rect(0, 0, 100, 100));
                 }),
             };
diff --git a/tests/Avalonia.RenderTests/Media/TextFormatting/TextLayoutTests.cs b/tests/Avalonia.RenderTests/Media/TextFormatting/TextLayoutTests.cs
index 7b128076cd..65fd670415 100644
--- a/tests/Avalonia.RenderTests/Media/TextFormatting/TextLayoutTests.cs
+++ b/tests/Avalonia.RenderTests/Media/TextFormatting/TextLayoutTests.cs
@@ -312,7 +312,7 @@ namespace Avalonia.Direct2D1.RenderTests.Media
                     var rotate = Matrix.CreateTranslation(-100, -100) *
                         Matrix.CreateRotation(MathUtilities.Deg2Rad(90)) *
                         Matrix.CreateTranslation(100, 100);
-                    using var transform = c.PushPreTransform(rotate);
+                    using var transform = c.PushTransform(rotate);
                     c.DrawRectangle(Brushes.Yellow, null, rect);
                     t.Draw(c, rect.Position);
                 }),
diff --git a/tests/Avalonia.Skia.UnitTests/Media/TextFormatting/TextFormatterTests.cs b/tests/Avalonia.Skia.UnitTests/Media/TextFormatting/TextFormatterTests.cs
index ce974472e7..cdcaadeff8 100644
--- a/tests/Avalonia.Skia.UnitTests/Media/TextFormatting/TextFormatterTests.cs
+++ b/tests/Avalonia.Skia.UnitTests/Media/TextFormatting/TextFormatterTests.cs
@@ -792,7 +792,7 @@ namespace Avalonia.Skia.UnitTests.Media.TextFormatting
             public override double Baseline => 0;
             public override void Draw(DrawingContext drawingContext, Point origin)
             {
-                using (drawingContext.PushPreTransform(Matrix.CreateTranslation(new Vector(origin.X, 0))))
+                using (drawingContext.PushTransform(Matrix.CreateTranslation(new Vector(origin.X, 0))))
                 {
                     drawingContext.FillRectangle(_fill, _rect);
                 }