Merge branch 'master' into remove-obsolete-members-from-avalonia.base-namespace

.github/PULL_REQUEST_TEMPLATE.md

@@ -21,7 +21,7 @@
 - [ ] Consider submitting a PR to https://github.com/AvaloniaUI/Documentation with user documentation
 
 ## Breaking changes
-<!--- List any breaking changes here. When the PR is merged please add an entry to https://github.com/AvaloniaUI/Avalonia/wiki/Breaking-Changes -->
+<!--- List any breaking changes here. -->
 
 ## Obsoletions / Deprecations
 <!--- Obsolete and Deprecated attributes on APIs MUST only be included when discussed with Core team. @grokys, @kekekeks & @danwalmsley -->

build/HarfBuzzSharp.props

@@ -1,7 +1,7 @@
 <Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <ItemGroup>
-    <PackageReference Include="HarfBuzzSharp" Version="2.8.2" />
-    <PackageReference Condition="'$(IncludeLinuxSkia)' == 'true'" Include="HarfBuzzSharp.NativeAssets.Linux" Version="2.8.2" />
-    <PackageReference Condition="'$(IncludeWasmSkia)' == 'true'" Include="HarfBuzzSharp.NativeAssets.WebAssembly" Version="2.8.2" />
+    <PackageReference Include="HarfBuzzSharp" Version="2.8.2.1-preview.108" />
+    <PackageReference Condition="'$(IncludeLinuxSkia)' == 'true'" Include="HarfBuzzSharp.NativeAssets.Linux" Version="2.8.2.1-preview.108" />
+    <PackageReference Condition="'$(IncludeWasmSkia)' == 'true'" Include="HarfBuzzSharp.NativeAssets.WebAssembly" Version="2.8.2.1-preview.108" />
   </ItemGroup>
 </Project>

build/SkiaSharp.props

@@ -1,7 +1,7 @@
 <Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <ItemGroup>
-    <PackageReference Include="SkiaSharp" Version="2.88.1-preview.1" />
-    <PackageReference Condition="'$(IncludeLinuxSkia)' == 'true'" Include="SkiaSharp.NativeAssets.Linux" Version="2.88.1-preview.1" />
-    <PackageReference Condition="'$(IncludeWasmSkia)' == 'true'" Include="SkiaSharp.NativeAssets.WebAssembly" Version="2.88.1-preview.1" />
+    <PackageReference Include="SkiaSharp" Version="2.88.1-preview.108" />
+    <PackageReference Condition="'$(IncludeLinuxSkia)' == 'true'" Include="SkiaSharp.NativeAssets.Linux" Version="2.88.1-preview.108" />
+    <PackageReference Condition="'$(IncludeWasmSkia)' == 'true'" Include="SkiaSharp.NativeAssets.WebAssembly" Version="2.88.1-preview.108" />
   </ItemGroup>
 </Project>

native/Avalonia.Native/src/OSX/WindowImpl.mm

@@ -121,7 +121,7 @@ void WindowImpl::BringToFront()
 {
     if(Window != nullptr)
     {
-        if (![Window isMiniaturized])
+        if ([Window isVisible] && ![Window isMiniaturized])
         {
             if(IsDialog())
             {

samples/ControlCatalog/MainView.xaml.cs

@@ -22,8 +22,8 @@ namespace ControlCatalog
 
             if (AvaloniaLocator.Current?.GetService<IRuntimePlatform>()?.GetRuntimeInfo().IsDesktop == true)
             {
-                IList tabItems = ((IList)sideBar.Items);
-                tabItems.Add(new TabItem()
+                var tabItems = (sideBar.Items as IList);
+                tabItems?.Add(new TabItem()
                 {
                     Header = "Screens",
                     Content = new ScreenPage()
@@ -36,7 +36,7 @@ namespace ControlCatalog
             {
                 if (themes.SelectedItem is CatalogTheme theme)
                 {
-                    var themeStyle = Application.Current.Styles[0];
+                    var themeStyle = Application.Current!.Styles[0];
                     if (theme == CatalogTheme.FluentLight)
                     {
                         if (App.Fluent.Mode != FluentThemeMode.Light)

samples/ControlCatalog/Models/Person.cs

@@ -85,7 +85,7 @@ namespace ControlCatalog.Models
             }
             else
             {
-                if (_errorLookup.TryGetValue(propertyName, out List<string> errorList))
+                if (_errorLookup.TryGetValue(propertyName, out var errorList))
                 {
                     errorList.Clear();
                     errorList.Add(error!);
@@ -114,12 +114,12 @@ namespace ControlCatalog.Models
             PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
         }
 
-        public IEnumerable? GetErrors(string propertyName)
+        public IEnumerable GetErrors(string? propertyName)
         {
-            if (_errorLookup.TryGetValue(propertyName, out List<string> errorList))
+            if (propertyName is { } && _errorLookup.TryGetValue(propertyName, out var errorList))
                 return errorList;
             else
-                return null;
+                return Array.Empty<object>();
         }
     }
 }

samples/ControlCatalog/Pages/AutoCompleteBoxPage.xaml

@@ -28,7 +28,7 @@
       </StackPanel>
       <StackPanel>
         <TextBlock Text="MinimumPopulateDelay: 1s" />
-        <AutoCompleteBox MinimumPopulateDelay="1" />
+        <AutoCompleteBox MinimumPopulateDelay="00:00:01" />
       </StackPanel>
       <StackPanel>
         <TextBlock Text="MaxDropDownHeight: 60" />

samples/ControlCatalog/Pages/AutoCompleteBoxPage.xaml.cs

@@ -1,8 +1,6 @@
 using Avalonia.Controls;
 using Avalonia.LogicalTree;
-using Avalonia.Markup;
 using Avalonia.Markup.Xaml;
-using Avalonia.Markup.Data;
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -161,23 +159,23 @@ namespace ControlCatalog.Pages
         private bool LastWordContains(string? searchText, string? item)
         {
             var words = searchText?.Split(' ') ?? Array.Empty<string>();
-            var options = Sentences.Select(x => x.First).ToArray();
+            var options = Sentences.Select(x => x.First)
+                .ToArray<LinkedListNode<string>?>();
             for (var i = 0; i < words.Length; ++i)
             {
                 var word = words[i];
                 for (var j = 0; word is { } && j < options.Length; ++j)
                 {
-                    var option = options[j];
-                    if (option == null)
-                        continue;
-
-                    if (i == words.Length - 1)
-                    {
-                        options[j] = option.Value.ToLower().Contains(word.ToLower()) ? option : null;
-                    }
-                    else
+                    if (options[i] is { } option)
                     {
-                        options[j] = option.Value.Equals(word, StringComparison.InvariantCultureIgnoreCase) ? option.Next : null;
+                        if (i == words.Length - 1)
+                        {
+                            options[j] = option.Value.ToLower().Contains(word.ToLower()) ? option : null;
+                        }
+                        else
+                        {
+                            options[j] = option.Value.Equals(word, StringComparison.InvariantCultureIgnoreCase) ? option.Next : null;
+                        }
                     }
                 }
             }

samples/ControlCatalog/Pages/ButtonSpinnerPage.xaml.cs

@@ -21,20 +21,23 @@ namespace ControlCatalog.Pages
         public void OnSpin(object sender, SpinEventArgs e)
         {
             var spinner = (ButtonSpinner)sender;
-            var txtBox = (TextBlock)spinner.Content;
 
-            int value = Array.IndexOf(_mountains, txtBox?.Text);
-            if (e.Direction == SpinDirection.Increase)
-                value++;
-            else
-                value--;
+            if (spinner.Content is TextBlock txtBox)
+            {
+                int value = Array.IndexOf(_mountains, txtBox.Text);
+                if (e.Direction == SpinDirection.Increase)
+                    value++;
+                else
+                    value--;
 
-            if (value < 0)
-                value = _mountains.Length - 1;
-            else if (value >= _mountains.Length)
-                value = 0;
+                if (value < 0)
+                    value = _mountains.Length - 1;
+                else if (value >= _mountains.Length)
+                    value = 0;
+
+                txtBox.Text = _mountains[value];
+            }
 
-            txtBox.Text = _mountains[value];
         }
 
         private readonly string[] _mountains = new[]

samples/ControlCatalog/Pages/ButtonsPage.xaml.cs

@@ -19,7 +19,7 @@ namespace ControlCatalog.Pages
             AvaloniaXamlLoader.Load(this);
         }
 
-        public void OnRepeatButtonClick(object sender, object args)
+        public void OnRepeatButtonClick(object? sender, object args)
         {
             repeatButtonClickCount++;
             var textBlock = this.Get<TextBlock>("RepeatButtonTextBlock");

samples/ControlCatalog/Pages/CarouselPage.xaml.cs

@@ -33,7 +33,7 @@ namespace ControlCatalog.Pages
 
         }
 
-        private void TransitionChanged(object sender, SelectionChangedEventArgs e)
+        private void TransitionChanged(object? sender, SelectionChangedEventArgs e)
         {
             switch (_transition.SelectedIndex)
             {

samples/ControlCatalog/Pages/ClipboardPage.xaml.cs

@@ -23,55 +23,79 @@ namespace ControlCatalog.Pages
             AvaloniaXamlLoader.Load(this);
         }
 
-        private async void CopyText(object sender, RoutedEventArgs args)
+        private async void CopyText(object? sender, RoutedEventArgs args)
         {
-            await Application.Current.Clipboard.SetTextAsync(ClipboardContent.Text);
+            if (Application.Current!.Clipboard is { } clipboard && ClipboardContent is { } clipboardContent)
+                await clipboard.SetTextAsync(clipboardContent.Text ?? String.Empty);
         }
 
-        private async void PasteText(object sender, RoutedEventArgs args)
+        private async void PasteText(object? sender, RoutedEventArgs args)
         {
-            ClipboardContent.Text = await Application.Current.Clipboard.GetTextAsync();
+            if(Application.Current!.Clipboard is { } clipboard)
+            {
+                ClipboardContent.Text = await clipboard.GetTextAsync();
+            }
         }
 
-        private async void CopyTextDataObject(object sender, RoutedEventArgs args)
+        private async void CopyTextDataObject(object? sender, RoutedEventArgs args)
         {
-            var dataObject = new DataObject();
-            dataObject.Set(DataFormats.Text, ClipboardContent.Text ?? string.Empty);
-            await Application.Current.Clipboard.SetDataObjectAsync(dataObject);
+            if (Application.Current!.Clipboard is { } clipboard)
+            {
+                var dataObject = new DataObject();
+                dataObject.Set(DataFormats.Text, ClipboardContent.Text ?? string.Empty);
+                await clipboard.SetDataObjectAsync(dataObject);
+            }
         }
 
-        private async void PasteTextDataObject(object sender, RoutedEventArgs args)
+        private async void PasteTextDataObject(object? sender, RoutedEventArgs args)
         {
-            ClipboardContent.Text = await Application.Current.Clipboard.GetDataAsync(DataFormats.Text) as string ?? string.Empty;
+            if (Application.Current!.Clipboard is { } clipboard)
+            {
+                ClipboardContent.Text = await clipboard.GetDataAsync(DataFormats.Text) as string ?? string.Empty;
+            }
         }
 
-        private async void CopyFilesDataObject(object sender, RoutedEventArgs args)
+        private async void CopyFilesDataObject(object? sender, RoutedEventArgs args)
         {
-            var files = ClipboardContent.Text.Split(new[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries);
-            if (files.Length == 0)
+            if (Application.Current!.Clipboard is { } clipboard)
             {
-                return;
+                var files = (ClipboardContent.Text ?? String.Empty)
+                .Split(new[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries);
+                if (files.Length == 0)
+                {
+                    return;
+                }
+                var dataObject = new DataObject();
+                dataObject.Set(DataFormats.FileNames, files);
+                await clipboard.SetDataObjectAsync(dataObject);
             }
-            var dataObject = new DataObject();
-            dataObject.Set(DataFormats.FileNames, files);
-            await Application.Current.Clipboard.SetDataObjectAsync(dataObject);
         }
 
-        private async void PasteFilesDataObject(object sender, RoutedEventArgs args)
+        private async void PasteFilesDataObject(object? sender, RoutedEventArgs args)
         {
-            var fiels = await Application.Current.Clipboard.GetDataAsync(DataFormats.FileNames) as IEnumerable<string>;
-            ClipboardContent.Text = fiels != null ? string.Join(Environment.NewLine, fiels) : string.Empty;
+            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;
+            }
         }
 
         private async void GetFormats(object sender, RoutedEventArgs args)
         {
-            var formats = await Application.Current.Clipboard.GetFormatsAsync();
-            ClipboardContent.Text = string.Join(Environment.NewLine, formats);
+            if (Application.Current!.Clipboard is { } clipboard)
+            {
+                var formats = await clipboard.GetFormatsAsync();
+                ClipboardContent.Text = string.Join(Environment.NewLine, formats);
+            }
         }
 
         private async void Clear(object sender, RoutedEventArgs args)
         {
-            await Application.Current.Clipboard.ClearAsync();
+            if (Application.Current!.Clipboard is { } clipboard)
+            {
+                await clipboard.ClearAsync();
+            }
+                
         }
     }
 }

samples/ControlCatalog/Pages/ComboBoxPage.xaml.cs

@@ -17,7 +17,7 @@ namespace ControlCatalog.Pages
         private void InitializeComponent()
         {
             AvaloniaXamlLoader.Load(this);
-            var fontComboBox = this.Find<ComboBox>("fontComboBox");
+            var fontComboBox = this.Get<ComboBox>("fontComboBox");
             fontComboBox.Items = FontManager.Current.GetInstalledFontFamilyNames().Select(x => new FontFamily(x));
             fontComboBox.SelectedIndex = 0;
         }

samples/ControlCatalog/Pages/CompositionPage.axaml.cs

@@ -1,14 +1,8 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
-using System.Numerics;
-using System.Threading.Tasks;
 using Avalonia;
 using Avalonia.Controls;
-using Avalonia.Controls.Primitives;
-using Avalonia.Interactivity;
 using Avalonia.Markup.Xaml;
-using Avalonia.Markup.Xaml.Templates;
 using Avalonia.Media;
 using Avalonia.Rendering.Composition;
 using Avalonia.Rendering.Composition.Animations;
@@ -18,7 +12,7 @@ namespace ControlCatalog.Pages;
 
 public partial class CompositionPage : UserControl
 {
-    private ImplicitAnimationCollection _implicitAnimations;
+    private ImplicitAnimationCollection? _implicitAnimations;
 
     public CompositionPage()
     {
@@ -28,7 +22,7 @@ public partial class CompositionPage : UserControl
     protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
     {
         base.OnAttachedToVisualTree(e);
-        this.FindControl<ItemsControl>("Items").Items = CreateColorItems();
+        this.Get<ItemsControl>("Items").Items = CreateColorItems();
     }
 
     private List<CompositionPageColorItem> CreateColorItems()
@@ -115,7 +109,6 @@ public partial class CompositionPage : UserControl
 
     public static void SetEnableAnimations(Border border, bool value)
     {
-        
         var page = border.FindAncestorOfType<CompositionPage>();
         if (page == null)
         {
@@ -127,8 +120,11 @@ public partial class CompositionPage : UserControl
             return;
 
         page.EnsureImplicitAnimations();
-        ElementComposition.GetElementVisual((Visual)border.GetVisualParent()).ImplicitAnimations =
-            page._implicitAnimations;
+        if (border.GetVisualParent() is Visual visualParent 
+            && ElementComposition.GetElementVisual(visualParent) is CompositionVisual compositionVisual)
+        {
+            compositionVisual.ImplicitAnimations = page._implicitAnimations;
+        }
     }
 }
 
@@ -150,4 +146,4 @@ public class CompositionPageColorItem
     {
         Color = color;
     }
-}
+}

samples/ControlCatalog/Pages/ContextFlyoutPage.xaml.cs

@@ -52,13 +52,13 @@ namespace ControlCatalog.Pages
             base.OnDataContextChanged(e);
         }
 
-        private void ContextFlyoutPage_Closing(object sender, CancelEventArgs e)
+        private void ContextFlyoutPage_Closing(object? sender, CancelEventArgs e)
         {
             var cancelCloseCheckBox = this.FindControl<CheckBox>("CancelCloseCheckBox");
             e.Cancel = cancelCloseCheckBox?.IsChecked ?? false;
         }
 
-        private void ContextFlyoutPage_Opening(object sender, EventArgs e)
+        private void ContextFlyoutPage_Opening(object? sender, EventArgs e)
         {
             if (e is CancelEventArgs cancelArgs)
             {
@@ -67,20 +67,20 @@ namespace ControlCatalog.Pages
             }
         }
 
-        private void CloseFlyout(object sender, RoutedEventArgs e)
+        private void CloseFlyout(object? sender, RoutedEventArgs e)
         {
             _textBox.ContextFlyout?.Hide();
         }
 
-        public void CustomContextRequested(object sender, ContextRequestedEventArgs e)
+        public void CustomContextRequested(object? sender, ContextRequestedEventArgs e)
         {
-            var border = (Border)sender;
-            var textBlock = (TextBlock)border.Child;
-
-            textBlock.Text = e.TryGetPosition(border, out var point)
-                ? $"Context was requested with pointer at: {point.X:N0}, {point.Y:N0}"
-                : "Context was requested without pointer";
-            e.Handled = true;
+            if (sender is Border border && border.Child is TextBlock textBlock)
+            {
+                textBlock.Text = e.TryGetPosition(border, out var point)
+                    ? $"Context was requested with pointer at: {point.X:N0}, {point.Y:N0}"
+                    : "Context was requested without pointer";
+                e.Handled = true;
+            }
         }
 
         private void InitializeComponent()

samples/ControlCatalog/Pages/ContextMenuPage.xaml.cs

@@ -35,30 +35,31 @@ namespace ControlCatalog.Pages
             base.OnDataContextChanged(e);
         }
 
-        private void ContextFlyoutPage_Closing(object sender, CancelEventArgs e)
+        private void ContextFlyoutPage_Closing(object? sender, CancelEventArgs e)
         {
             var cancelCloseCheckBox = this.FindControl<CheckBox>("CancelCloseCheckBox");
-            e.Cancel = cancelCloseCheckBox.IsChecked ?? false;
+            e.Cancel = cancelCloseCheckBox?.IsChecked ?? false;
         }
 
-        private void ContextFlyoutPage_Opening(object sender, EventArgs e)
+        private void ContextFlyoutPage_Opening(object? sender, EventArgs e)
         {
             if (e is CancelEventArgs cancelArgs)
             {
                 var cancelCloseCheckBox = this.FindControl<CheckBox>("CancelOpenCheckBox");
-                cancelArgs.Cancel = cancelCloseCheckBox.IsChecked ?? false;
+                cancelArgs.Cancel = cancelCloseCheckBox?.IsChecked ?? false;
             }
         }
 
-        public void CustomContextRequested(object sender, ContextRequestedEventArgs e)
+        public void CustomContextRequested(object? sender, ContextRequestedEventArgs e)
         {
-            var border = (Border)sender;
-            var textBlock = (TextBlock)border.Child;
+            if (sender is Border border && border.Child is TextBlock textBlock)
+            {
+                textBlock.Text = e.TryGetPosition(border, out var point)
+                    ? $"Context was requested with pointer at: {point.X:N0}, {point.Y:N0}"
+                    : "Context was requested without pointer";
+                e.Handled = true;
+            }
 
-            textBlock.Text = e.TryGetPosition(border, out var point)
-                ? $"Context was requested with pointer at: {point.X:N0}, {point.Y:N0}"
-                : "Context was requested without pointer";
-            e.Handled = true;
         }
 
         private void InitializeComponent()

samples/ControlCatalog/Pages/DataGridPage.xaml.cs

@@ -62,7 +62,7 @@ namespace ControlCatalog.Pages
             addButton.Click += (a, b) => collectionView3.AddNew();
         }
 
-        private void Dg1_LoadingRow(object sender, DataGridRowEventArgs e)
+        private void Dg1_LoadingRow(object? sender, DataGridRowEventArgs e)
         {
             e.Row.Header = e.Row.GetIndex() + 1;
         }
@@ -74,7 +74,7 @@ namespace ControlCatalog.Pages
 
         private class ReversedStringComparer : IComparer<object>, IComparer
         {
-            public int Compare(object x, object y)
+            public int Compare(object? x, object? y)
             {
                 if (x is string left && y is string right)
                 {

samples/ControlCatalog/Pages/DialogsPage.xaml.cs

@@ -111,9 +111,16 @@ namespace ControlCatalog.Pages
                     Title = "Select folder",
                     Directory = lastSelectedDirectory?.TryGetUri(out var path) == true ? path.LocalPath : null
                 }.ShowAsync(GetWindow());
-                lastSelectedDirectory = new BclStorageFolder(new System.IO.DirectoryInfo(result));
-                results.Items = new [] { result };
-                resultsVisible.IsVisible = result != null;
+                if (string.IsNullOrEmpty(result))
+                {
+                    resultsVisible.IsVisible = false;
+                }
+                else
+                {
+                    lastSelectedDirectory = new BclStorageFolder(new System.IO.DirectoryInfo(result));
+                    results.Items = new[] { result };
+                    resultsVisible.IsVisible = true;
+                }
             };
             this.Get<Button>("OpenBoth").Click += async delegate
             {

samples/ControlCatalog/Pages/DragAndDropPage.xaml.cs

@@ -1,9 +1,9 @@
-using Avalonia.Controls;
-using Avalonia.Input;
-using Avalonia.Markup.Xaml;
-using System;
+using System;
 using System.Linq;
 using System.Reflection;
+using Avalonia.Controls;
+using Avalonia.Input;
+using Avalonia.Markup.Xaml;
 
 namespace ControlCatalog.Pages
 {
@@ -27,9 +27,9 @@ namespace ControlCatalog.Pages
         void SetupDnd(string suffix, Action<DataObject> factory, DragDropEffects effects)
         {
             var dragMe = this.Get<Border>("DragMe" + suffix);
-            var dragState = this.Get<TextBlock>("DragState"+suffix);
+            var dragState = this.Get<TextBlock>("DragState" + suffix);
 
-            async void DoDrag(object sender, Avalonia.Input.PointerPressedEventArgs e)
+            async void DoDrag(object? sender, Avalonia.Input.PointerPressedEventArgs e)
             {
                 var dragData = new DataObject();
                 factory(dragData);
@@ -55,7 +55,7 @@ namespace ControlCatalog.Pages
                 }
             }
 
-            void DragOver(object sender, DragEventArgs e)
+            void DragOver(object? sender, DragEventArgs e)
             {
                 if (e.Source is Control c && c.Name == "MoveTarget")
                 {
@@ -73,7 +73,7 @@ namespace ControlCatalog.Pages
                     e.DragEffects = DragDropEffects.None;
             }
 
-            void Drop(object sender, DragEventArgs e)
+            void Drop(object? sender, DragEventArgs e)
             {
                 if (e.Source is Control c && c.Name == "MoveTarget")
                 {
@@ -83,11 +83,11 @@ namespace ControlCatalog.Pages
                 {
                     e.DragEffects = e.DragEffects & (DragDropEffects.Copy);
                 }
-                
+
                 if (e.Data.Contains(DataFormats.Text))
                     _DropState.Text = e.Data.GetText();
                 else if (e.Data.Contains(DataFormats.FileNames))
-                    _DropState.Text = string.Join(Environment.NewLine, e.Data.GetFileNames());
+                    _DropState.Text = string.Join(Environment.NewLine, e.Data.GetFileNames() ?? Array.Empty<string>());
                 else if (e.Data.Contains(CustomFormat))
                     _DropState.Text = "Custom: " + e.Data.Get(CustomFormat);
             }

samples/ControlCatalog/Pages/FlyoutsPage.axaml.cs

@@ -20,7 +20,7 @@ namespace ControlCatalog.Pages
             SetXamlTexts();
         }
 
-        private void Afp_DoubleTapped(object sender, RoutedEventArgs e)
+        private void Afp_DoubleTapped(object? sender, RoutedEventArgs e)
         {
             if (sender is Panel p)
             {

samples/ControlCatalog/Pages/ItemsRepeaterPage.xaml.cs

@@ -123,7 +123,7 @@ namespace ControlCatalog.Pages
             element.BringIntoView();
         }
 
-        private void RepeaterClick(object sender, PointerPressedEventArgs e)
+        private void RepeaterClick(object? sender, PointerPressedEventArgs e)
         {
             if ((e.Source as TextBlock)?.DataContext is ItemsRepeaterPageViewModel.Item item)
             {
@@ -132,7 +132,7 @@ namespace ControlCatalog.Pages
             }
         }
 
-        private void RepeaterOnKeyDown(object sender, KeyEventArgs e)
+        private void RepeaterOnKeyDown(object? sender, KeyEventArgs e)
         {
             if (e.Key == Key.F5)
             {
@@ -140,17 +140,17 @@ namespace ControlCatalog.Pages
             }
         }
 
-        private void scrollToLast_Click(object sender, Avalonia.Interactivity.RoutedEventArgs e)
+        private void scrollToLast_Click(object? sender, Avalonia.Interactivity.RoutedEventArgs e)
         {
             ScrollTo(_viewModel.Items.Count - 1);
         }
 
-        private void scrollToRandom_Click(object sender, Avalonia.Interactivity.RoutedEventArgs e)
+        private void scrollToRandom_Click(object? sender, Avalonia.Interactivity.RoutedEventArgs e)
         {
             ScrollTo(_random.Next(_viewModel.Items.Count - 1));
         }
 
-        private void scrollToSelected_Click(object sender, Avalonia.Interactivity.RoutedEventArgs e)
+        private void scrollToSelected_Click(object? sender, Avalonia.Interactivity.RoutedEventArgs e)
         {
             ScrollTo(_selectedIndex);
         }

samples/ControlCatalog/Pages/NumericUpDownPage.xaml.cs

@@ -2,9 +2,7 @@
 using System.Collections.Generic;
 using System.Globalization;
 using System.Linq;
-using Avalonia;
 using Avalonia.Controls;
-using Avalonia.Controls.Primitives;
 using Avalonia.Markup.Xaml;
 using MiniMvvm;
 
@@ -29,7 +27,7 @@ namespace ControlCatalog.Pages
     public class NumbersPageViewModel : ViewModelBase
     {
         private IList<FormatObject>? _formats;
-        private FormatObject _selectedFormat;
+        private FormatObject? _selectedFormat;
         private IList<Location>? _spinnerLocations;
 
         private double _doubleValue;
@@ -89,7 +87,7 @@ namespace ControlCatalog.Pages
             .Where(c => new[] { "en-US", "en-GB", "fr-FR", "ar-DZ", "zh-CH", "cs-CZ" }.Contains(c.Name))
             .ToArray();
 
-        public FormatObject SelectedFormat
+        public FormatObject? SelectedFormat
         {
             get { return _selectedFormat; }
             set { this.RaiseAndSetIfChanged(ref _selectedFormat, value); }

samples/ControlCatalog/Pages/OpenGlPage.xaml.cs

@@ -68,7 +68,7 @@ namespace ControlCatalog.Pages
             set => SetAndRaise(DiscoProperty, ref _disco, value);
         }
 
-        private string _info;
+        private string _info = string.Empty;
 
         public static readonly DirectProperty<OpenGlPageControl, string> InfoProperty =
             AvaloniaProperty.RegisterDirect<OpenGlPageControl, string>("Info", o => o.Info, (o, v) => o.Info = v);
@@ -205,7 +205,7 @@ namespace ControlCatalog.Pages
         public OpenGlPageControl()
         {
             var name = typeof(OpenGlPage).Assembly.GetManifestResourceNames().First(x => x.Contains("teapot.bin"));
-            using (var sr = new BinaryReader(typeof(OpenGlPage).Assembly.GetManifestResourceStream(name)))
+            using (var sr = new BinaryReader(typeof(OpenGlPage).Assembly.GetManifestResourceStream(name)!))
             {
                 var buf = new byte[sr.ReadInt32()];
                 sr.Read(buf, 0, buf.Length);
@@ -345,7 +345,7 @@ namespace ControlCatalog.Pages
                     0.01f, 1000);
 
 
-            var view = Matrix4x4.CreateLookAt(new Vector3(25, 25, 25), new Vector3(), new Vector3(0, -1, 0));
+            var view = Matrix4x4.CreateLookAt(new Vector3(25, 25, 25), new Vector3(), new Vector3(0, 1, 0));
             var model = Matrix4x4.CreateFromYawPitchRoll(_yaw, _pitch, _roll);
             var modelLoc = GL.GetUniformLocationString(_shaderProgram, "uModel");
             var viewLoc = GL.GetUniformLocationString(_shaderProgram, "uView");

samples/ControlCatalog/Pages/PointersPage.xaml.cs

@@ -1,8 +1,6 @@
 using System;
-using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Input;
-using Avalonia.Interactivity;
 using Avalonia.Markup.Xaml;
 
 namespace ControlCatalog.Pages;
@@ -31,28 +29,33 @@ public class PointersPage : UserControl
         border2.PointerExited += Border_PointerUpdated;
     }
 
-    private void Border_PointerUpdated(object sender, PointerEventArgs e)
+    private void Border_PointerUpdated(object? sender, PointerEventArgs e)
     {
-        var textBlock = (TextBlock)((Border)sender).Child;
-        var position = e.GetPosition((Border)sender);
-        textBlock.Text = @$"Type: {e.Pointer.Type}
+        if (sender is Border border && border.Child is TextBlock textBlock)
+        {
+            var position = e.GetPosition(border);
+            textBlock.Text = @$"Type: {e.Pointer.Type}
 Captured: {e.Pointer.Captured == sender}
 PointerId: {e.Pointer.Id}
 Position: {(int)position.X} {(int)position.Y}";
-        e.Handled = true;
+            e.Handled = true;
+        }
     }
 
-    private void Border_PointerCaptureLost(object sender, PointerCaptureLostEventArgs e)
+    private void Border_PointerCaptureLost(object? sender, PointerCaptureLostEventArgs e)
     {
-        var textBlock = (TextBlock)((Border)sender).Child;
-        textBlock.Text = @$"Type: {e.Pointer.Type}
+        if (sender is Border border && border.Child is TextBlock textBlock)
+        {
+            textBlock.Text = @$"Type: {e.Pointer.Type}
 Captured: {e.Pointer.Captured == sender}
 PointerId: {e.Pointer.Id}
 Position: ??? ???";
-        e.Handled = true;
+            e.Handled = true;
+
+        }
     }
 
-    private void Border_PointerReleased(object sender, PointerReleasedEventArgs e)
+    private void Border_PointerReleased(object? sender, PointerReleasedEventArgs e)
     {
         if (e.Pointer.Captured == sender)
         {
@@ -65,9 +68,9 @@ Position: ??? ???";
         }
     }
 
-    private void Border_PointerPressed(object sender, PointerPressedEventArgs e)
+    private void Border_PointerPressed(object? sender, PointerPressedEventArgs e)
     {
-        e.Pointer.Capture((Border)sender);
+        e.Pointer.Capture(sender as Border);
         e.Handled = true;
     }
 

samples/ControlCatalog/ViewModels/TransitioningContentControlPageViewModel.cs

@@ -117,9 +117,9 @@ namespace ControlCatalog.ViewModels
             PageTransitions[3].Transition = new PageSlide(TimeSpan.FromMilliseconds(Duration), PageSlide.SlideAxis.Vertical);
 
             var compositeTransition = new CompositePageTransition();
-            compositeTransition.PageTransitions.Add(PageTransitions[1].Transition);
-            compositeTransition.PageTransitions.Add(PageTransitions[2].Transition);
-            compositeTransition.PageTransitions.Add(PageTransitions[3].Transition);
+            compositeTransition.PageTransitions.Add(PageTransitions[1].Transition!);
+            compositeTransition.PageTransitions.Add(PageTransitions[2].Transition!);
+            compositeTransition.PageTransitions.Add(PageTransitions[3].Transition!);
             PageTransitions[4].Transition = compositeTransition;
 
             PageTransitions[5].Transition = new CustomTransition(TimeSpan.FromMilliseconds(Duration));

samples/IntegrationTestApp/MainWindow.axaml.cs

@@ -1,4 +1,3 @@
-using System;
 using System.Collections.Generic;
 using System.Linq;
 using Avalonia;
@@ -31,20 +30,23 @@ namespace IntegrationTestApp
 
         private void InitializeViewMenu()
         {
-            var mainTabs = this.FindControl<TabControl>("MainTabs");
+            var mainTabs = this.Get<TabControl>("MainTabs");
             var viewMenu = (NativeMenuItem)NativeMenu.GetMenu(this).Items[1];
 
-            foreach (TabItem tabItem in mainTabs.Items)
+            if (mainTabs.Items is not null)
             {
-                var menuItem = new NativeMenuItem
+                foreach (TabItem tabItem in mainTabs.Items)
                 {
-                    Header = (string)tabItem.Header!,
-                    IsChecked = tabItem.IsSelected,
-                    ToggleType = NativeMenuItemToggleType.Radio,
-                };
-
-                menuItem.Click += (s, e) => tabItem.IsSelected = true;
-                viewMenu.Menu.Items.Add(menuItem);
+                    var menuItem = new NativeMenuItem
+                    {
+                        Header = (string)tabItem.Header!,
+                        IsChecked = tabItem.IsSelected,
+                        ToggleType = NativeMenuItemToggleType.Radio,
+                    };
+
+                    menuItem.Click += (s, e) => tabItem.IsSelected = true;
+                    viewMenu?.Menu?.Items.Add(menuItem);
+                }
             }
         }
 
@@ -99,6 +101,7 @@ namespace IntegrationTestApp
 
             foreach (var window in lifetime.Windows)
             {
+                window.Show();
                 if (window.WindowState == WindowState.Minimized)
                     window.WindowState = WindowState.Normal;
             }
@@ -106,8 +109,8 @@ namespace IntegrationTestApp
 
         private void MenuClicked(object? sender, RoutedEventArgs e)
         {
-            var clickedMenuItemTextBlock = this.FindControl<TextBlock>("ClickedMenuItem");
-            clickedMenuItemTextBlock.Text = ((MenuItem)sender!).Header.ToString();
+            var clickedMenuItemTextBlock = this.Get<TextBlock>("ClickedMenuItem");
+            clickedMenuItemTextBlock.Text = (sender as MenuItem)?.Header?.ToString();
         }
 
         private void OnButtonClick(object? sender, RoutedEventArgs e)
@@ -115,13 +118,13 @@ namespace IntegrationTestApp
             var source = e.Source as Button;
 
             if (source?.Name == "ComboBoxSelectionClear")
-                this.FindControl<ComboBox>("BasicComboBox").SelectedIndex = -1;
+                this.Get<ComboBox>("BasicComboBox").SelectedIndex = -1;
             if (source?.Name == "ComboBoxSelectFirst")
-                this.FindControl<ComboBox>("BasicComboBox").SelectedIndex = 0;
+                this.Get<ComboBox>("BasicComboBox").SelectedIndex = 0;
             if (source?.Name == "ListBoxSelectionClear")
-                this.FindControl<ListBox>("BasicListBox").SelectedIndex = -1;
+                this.Get<ListBox>("BasicListBox").SelectedIndex = -1;
             if (source?.Name == "MenuClickedMenuItemReset")
-                this.FindControl<TextBlock>("ClickedMenuItem").Text = "None";
+                this.Get<TextBlock>("ClickedMenuItem").Text = "None";
             if (source?.Name == "ShowWindow")
                 ShowWindow();
             if (source?.Name == "SendToBack")

samples/IntegrationTestApp/ShowWindowTest.axaml

@@ -3,7 +3,7 @@
         x:Class="IntegrationTestApp.ShowWindowTest"
         Name="SecondaryWindow"
         Title="Show Window Test">
-  <Grid ColumnDefinitions="Auto,Auto" RowDefinitions="Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto">
+  <Grid ColumnDefinitions="Auto,Auto" RowDefinitions="Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto">
     <Label Grid.Column="0" Grid.Row="1">Client Size</Label>
     <TextBox Name="ClientSize" Grid.Column="1" Grid.Row="1" IsReadOnly="True"
              Text="{Binding ClientSize, Mode=OneWay}"/>
@@ -31,5 +31,6 @@
       <ComboBoxItem>Maximized</ComboBoxItem>
       <ComboBoxItem>Fullscreen</ComboBoxItem>
     </ComboBox>
+    <Button Name="HideButton" Grid.Row="8" Command="{Binding $parent[Window].Hide}">Hide</Button>
   </Grid>
 </Window>

samples/RenderDemo/Pages/TextFormatterPage.axaml.cs

@@ -78,7 +78,7 @@ namespace RenderDemo.Pages
                 _defaultProperties = defaultProperties;
             }
             
-            public TextRun? GetTextRun(int textSourceIndex)
+            public TextRun GetTextRun(int textSourceIndex)
             {
                 if (textSourceIndex >= _text.Length * 2 + TextRun.DefaultTextSourceLength)
                 {
@@ -107,7 +107,7 @@ namespace RenderDemo.Pages
             public Control Control => _control;
             public override Size Size => _control.DesiredSize;
             public override double Baseline => 0;
-            public override TextRunProperties? Properties { get; }
+            public override TextRunProperties Properties { get; }
 
             public override void Draw(DrawingContext drawingContext, Point origin)
             {

src/Android/Avalonia.Android/AndroidPlatform.cs

@@ -17,10 +17,8 @@ namespace Avalonia
     {
         public static T UseAndroid<T>(this T builder) where T : AppBuilderBase<T>, new()
         {
-            var options = AvaloniaLocator.Current.GetService<AndroidPlatformOptions>() ?? new AndroidPlatformOptions();
-
             return builder
-                .UseWindowingSubsystem(() => AndroidPlatform.Initialize(options), "Android")
+                .UseWindowingSubsystem(() => AndroidPlatform.Initialize(), "Android")
                 .UseSkia();
         }
     }
@@ -45,9 +43,9 @@ namespace Avalonia.Android
 
         internal static Compositor Compositor { get; private set; }
 
-        public static void Initialize(AndroidPlatformOptions options)
+        public static void Initialize()
         {
-            Options = options;
+            Options = AvaloniaLocator.Current.GetService<AndroidPlatformOptions>() ?? new AndroidPlatformOptions();
 
             AvaloniaLocator.CurrentMutable
                 .Bind<IClipboard>().ToTransient<ClipboardImpl>()
@@ -61,12 +59,12 @@ namespace Avalonia.Android
                 .Bind<IRenderLoop>().ToConstant(new RenderLoop())
                 .Bind<PlatformHotkeyConfiguration>().ToSingleton<PlatformHotkeyConfiguration>();
 
-            if (options.UseGpu)
+            if (Options.UseGpu)
             {
                 EglPlatformOpenGlInterface.TryInitialize();
             }
             
-            if (options.UseCompositor)
+            if (Options.UseCompositor)
             {
                 Compositor = new Compositor(
                     AvaloniaLocator.Current.GetRequiredService<IRenderLoop>(),

src/Android/Avalonia.Android/AndroidThreadingInterface.cs

@@ -27,46 +27,33 @@ namespace Avalonia.Android
         {
             if (interval.TotalMilliseconds < 10)
                 interval = TimeSpan.FromMilliseconds(10);
-            object l = new object();
+
             var stopped = false;
             Timer timer = null;
-            var scheduled = false;
             timer = new Timer(_ =>
             {
-                lock (l)
+                if (stopped)
+                    return;
+
+                EnsureInvokeOnMainThread(() =>
                 {
-                    if (stopped)
+                    try
                     {
-                        timer.Dispose();
-                        return;
+                        tick();
                     }
-                    if (scheduled)
-                        return;
-                    scheduled = true;
-                    EnsureInvokeOnMainThread(() =>
+                    finally
                     {
-                        try
-                        {
-                            tick();
-                        }
-                        finally
-                        {
-                            lock (l)
-                            {
-                                scheduled = false;
-                            }
-                        }
-                    });
-                }
-            }, null, TimeSpan.Zero, interval);
+                        if (!stopped)
+                            timer.Change(interval, Timeout.InfiniteTimeSpan);
+                    }
+                });
+            },
+            null, interval, Timeout.InfiniteTimeSpan);
 
             return Disposable.Create(() =>
             {
-                lock (l)
-                {
-                    stopped = true;
-                    timer.Dispose();
-                }
+                stopped = true;
+                timer.Dispose();
             });
         }
 

src/Avalonia.Base/Input/PointerOverPreProcessor.cs

@@ -158,6 +158,8 @@ namespace Avalonia.Input
                     ClearPointerOver(pointer, root, timestamp, position, properties, inputModifiers);
                 }
             }
+
+            _lastPointer = (pointer, root.PointToScreen(position));
         }
 
         private void SetPointerOverToElement(IPointer pointer, IInputRoot root, IInputElement element,
@@ -195,7 +197,6 @@ namespace Avalonia.Input
             }
 
             el = root.PointerOverElement = element;
-            _lastPointer = (pointer, root.PointToScreen(position));
 
             e.RoutedEvent = InputElement.PointerEnteredEvent;
 

src/Avalonia.Base/Platform/Storage/FileIO/BclStorageFile.cs

@@ -12,6 +12,11 @@ public class BclStorageFile : IStorageBookmarkFile
 {
     private readonly FileInfo _fileInfo;
 
+    public BclStorageFile(string fileName)
+    {
+        _fileInfo = new FileInfo(fileName);
+    }
+
     public BclStorageFile(FileInfo fileInfo)
     {
         _fileInfo = fileInfo ?? throw new ArgumentNullException(nameof(fileInfo));
@@ -27,15 +32,14 @@ public class BclStorageFile : IStorageBookmarkFile
 
     public Task<StorageItemProperties> GetBasicPropertiesAsync()
     {
-        var props = new StorageItemProperties();
         if (_fileInfo.Exists)
         {
-            props = new StorageItemProperties(
+            return Task.FromResult(new StorageItemProperties(
                 (ulong)_fileInfo.Length,
                 _fileInfo.CreationTimeUtc,
-                _fileInfo.LastAccessTimeUtc);
+                _fileInfo.LastAccessTimeUtc));
         }
-        return Task.FromResult(props);
+        return Task.FromResult(new StorageItemProperties());
     }
 
     public Task<IStorageFolder?> GetParentAsync()

src/Avalonia.Base/Platform/Storage/FileIO/BclStorageFolder.cs

@@ -14,6 +14,15 @@ public class BclStorageFolder : IStorageBookmarkFolder
 {
     private readonly DirectoryInfo _directoryInfo;
 
+    public BclStorageFolder(string path)
+    {
+        _directoryInfo = new DirectoryInfo(path);
+        if (!_directoryInfo.Exists)
+        {
+            throw new ArgumentException("Directory must exist");
+        }
+    }
+
     public BclStorageFolder(DirectoryInfo directoryInfo)
     {
         _directoryInfo = directoryInfo ?? throw new ArgumentNullException(nameof(directoryInfo));

src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionTarget.cs

@@ -78,6 +78,13 @@ namespace Avalonia.Rendering.Composition.Server
 
             if (Root == null) 
                 return;
+
+            if ((_renderTarget as IRenderTargetWithCorruptionInfo)?.IsCorrupted == true)
+            {
+                _renderTarget!.Dispose();
+                _renderTarget = null;
+            }
+
             _renderTarget ??= _renderTargetFactory();
 
             Compositor.UpdateServerTime();

src/Avalonia.Base/Utilities/MathUtilities.cs

@@ -324,6 +324,41 @@ namespace Avalonia.Utilities
             return angle * 2 * Math.PI;
         }
 
+        /// <summary>
+        /// Calculates the point of an angle on an ellipse.
+        /// </summary>
+        /// <param name="centre">The centre point of the ellipse.</param>
+        /// <param name="radiusX">The x radius of the ellipse.</param>
+        /// <param name="radiusY">The y radius of the ellipse.</param>
+        /// <param name="angle">The angle in radians.</param>
+        /// <returns>A point on the ellipse.</returns>
+        public static Point GetEllipsePoint(Point centre, double radiusX, double radiusY, double angle)
+        {
+            return new Point(radiusX * Math.Cos(angle) + centre.X, radiusY * Math.Sin(angle) + centre.Y);
+        }
+
+        /// <summary>
+        /// Gets the minimum and maximum from the specified numbers.
+        /// </summary>
+        /// <param name="a">The first number.</param>
+        /// <param name="b">The second number.</param>
+        /// <returns>A tuple containing the minimum and maximum of the two specified numbers.</returns>
+        public static (double min, double max) GetMinMax(double a, double b)
+        {
+            return a < b ? (a, b) : (b, a);
+        }
+
+        /// <summary>
+        /// Gets the minimum and maximum from the specified number and the difference with that number.
+        /// </summary>
+        /// <param name="initialValue">The initial value to use.</param>
+        /// <param name="delta">The difference for <paramref name="initialValue"/>.</param>
+        /// <returns>A tuple containing the minimum and maximum of the specified number and the difference with that number.</returns>
+        public static (double min, double max) GetMinMaxFromDelta(double initialValue, double delta)
+        {
+            return GetMinMax(initialValue, initialValue + delta);
+        }
+
         private static void ThrowCannotBeGreaterThanException<T>(T min, T max)
         {
             throw new ArgumentException($"{min} cannot be greater than {max}.");

src/Avalonia.Controls.DataGrid/DataGrid.cs

@@ -2167,7 +2167,23 @@ namespace Avalonia.Controls
 
             return desiredSize;
         }
+        
+        /// <inheritdoc/>
+        protected override void OnDataContextBeginUpdate()
+        {
+            base.OnDataContextBeginUpdate();
 
+            NotifyDataContextPropertyForAllRowCells(GetAllRows(), true);
+        }
+
+        /// <inheritdoc/>
+        protected override void OnDataContextEndUpdate()
+        {
+            base.OnDataContextEndUpdate();
+
+            NotifyDataContextPropertyForAllRowCells(GetAllRows(), false);
+        }
+        
         /// <summary>
         /// Raises the BeginningEdit event.
         /// </summary>
@@ -3165,6 +3181,20 @@ namespace Avalonia.Controls
             }
         }
 
+        private static void NotifyDataContextPropertyForAllRowCells(IEnumerable<DataGridRow> rowSource, bool arg2)
+        {
+            foreach (DataGridRow row in rowSource)
+            {
+                foreach (DataGridCell cell in row.Cells)
+                {
+                    if (cell.Content is StyledElement cellContent)
+                    {
+                        DataContextProperty.Notifying?.Invoke(cellContent, arg2);
+                    }
+                }
+            }
+        }
+
         private void UpdateRowDetailsVisibilityMode(DataGridRowDetailsVisibilityMode newDetailsMode)
         {
             int itemCount = DataConnection.Count;

src/Avalonia.Controls/AutoCompleteBox.cs

@@ -392,6 +392,8 @@ namespace Avalonia.Controls
         private AutoCompleteSelector<object>? _itemSelector;
         private AutoCompleteSelector<string?>? _textSelector;
 
+        private readonly EventHandler _populateDropDownHandler;
+
         public static readonly RoutedEvent<SelectionChangedEventArgs> SelectionChangedEvent =
             RoutedEvent.Register<SelectionChangedEventArgs>(nameof(SelectionChanged), RoutingStrategies.Bubble, typeof(AutoCompleteBox));
 
@@ -668,6 +670,7 @@ namespace Avalonia.Controls
 
                 if (newValue == TimeSpan.Zero)
                 {
+                    _delayTimer.Tick -= _populateDropDownHandler;
                     _delayTimer = null;
                 }
             }
@@ -678,7 +681,7 @@ namespace Avalonia.Controls
                 if (_delayTimer == null)
                 {
                     _delayTimer = new DispatcherTimer();
-                    _delayTimer.Tick += PopulateDropDown;
+                    _delayTimer.Tick += _populateDropDownHandler;
                 }
 
                 // Set the new tick interval
@@ -864,6 +867,7 @@ namespace Avalonia.Controls
         /// </summary>
         public AutoCompleteBox()
         {
+            _populateDropDownHandler = PopulateDropDown;
             ClearView();
         }
 
@@ -1771,10 +1775,7 @@ namespace Avalonia.Controls
         /// <param name="e">The event arguments.</param>
         private void PopulateDropDown(object? sender, EventArgs e)
         {
-            if (_delayTimer != null)
-            {
-                _delayTimer.Stop();
-            }
+            _delayTimer?.Stop();
 
             // Update the prefix/search text.
             SearchText = Text;

src/Avalonia.Controls/Calendar/Calendar.cs

@@ -224,7 +224,7 @@ namespace Avalonia.Controls
     /// </para>
     /// </remarks>
     [TemplatePart(PART_ElementMonth, typeof(CalendarItem))]
-    [TemplatePart(PART_ElementRoot,  typeof(Panel))]
+    [TemplatePart(PART_ElementRoot, typeof(Panel))]
     public class Calendar : TemplatedControl
     {
         internal const int RowsPerMonth = 7;
@@ -338,14 +338,11 @@ namespace Avalonia.Controls
         /// <param name="e">The DependencyPropertyChangedEventArgs.</param>
         private void OnIsTodayHighlightedChanged(AvaloniaPropertyChangedEventArgs e)
         {
-            if (DisplayDate != null)
-            {
-                int i = DateTimeHelper.CompareYearMonth(DisplayDateInternal, DateTime.Today);
+            int i = DateTimeHelper.CompareYearMonth(DisplayDateInternal, DateTime.Today);
 
-                if (i > -2 && i < 2)
-                {
-                    UpdateMonths();
-                }
+            if (i > -2 && i < 2)
+            {
+                UpdateMonths();
             }
         }
 
@@ -655,7 +652,7 @@ namespace Avalonia.Controls
                 SelectedDatesChanged?.Invoke(this, e);
             }
         }
-        
+
         internal Collection<DateTime> RemovedItems { get; set; }
         internal DateTime? LastSelectedDateInternal { get; set; }
         internal DateTime? LastSelectedDate
@@ -914,7 +911,7 @@ namespace Avalonia.Controls
                 o => o.DisplayDateEnd,
                 (o, v) => o.DisplayDateEnd = v,
                 defaultBindingMode: BindingMode.TwoWay);
-        
+
         /// <summary>
         /// Gets or sets the last date to be displayed.
         /// </summary>
@@ -1242,7 +1239,7 @@ namespace Avalonia.Controls
                                     {
                                         b.IsSelected = false;
                                     }
-                                } 
+                                }
                             }
                         }
                     }
@@ -1278,7 +1275,7 @@ namespace Avalonia.Controls
 
         internal void OnPreviousClick()
         {
-            if (DisplayMode == CalendarMode.Month && DisplayDate != null)
+            if (DisplayMode == CalendarMode.Month)
             {
                 DateTime? d = DateTimeHelper.AddMonths(DateTimeHelper.DiscardDayTime(DisplayDate), -1);
                 if (d.HasValue)
@@ -1326,7 +1323,7 @@ namespace Avalonia.Controls
         }
         internal void OnNextClick()
         {
-            if (DisplayMode == CalendarMode.Month && DisplayDate != null)
+            if (DisplayMode == CalendarMode.Month)
             {
                 DateTime? d = DateTimeHelper.AddMonths(DateTimeHelper.DiscardDayTime(DisplayDate), 1);
                 if (d.HasValue)
@@ -1645,7 +1642,7 @@ namespace Avalonia.Controls
         {
             if (DisplayMode == CalendarMode.Month)
             {
-                if (LastSelectedDate.HasValue && DisplayDateInternal != null)
+                if (LastSelectedDate.HasValue)
                 {
                     // If a blackout day is inactive, when clicked on it, the
                     // previous inactive day which is not a blackout day can get
@@ -1897,24 +1894,21 @@ namespace Avalonia.Controls
             {
                 case CalendarMode.Month:
                     {
-                        if (DisplayDate != null)
-                        {
-                            DateTime? selectedDate = new DateTime(DisplayDateInternal.Year, DisplayDateInternal.Month, 1);
+                        DateTime? selectedDate = new DateTime(DisplayDateInternal.Year, DisplayDateInternal.Month, 1);
 
-                            if (DateTimeHelper.CompareYearMonth(DateTime.MaxValue, selectedDate.Value) > 0)
-                            {
-                                // since DisplayDate is not equal to
-                                // DateTime.MaxValue we are sure selectedDate is\
-                                // not null
-                                selectedDate = DateTimeHelper.AddMonths(selectedDate.Value, 1)!.Value;
-                                selectedDate = DateTimeHelper.AddDays(selectedDate.Value, -1)!.Value;
-                            }
-                            else
-                            {
-                                selectedDate = DateTime.MaxValue;
-                            }
-                            ProcessSelection(shift, selectedDate, null);
+                        if (DateTimeHelper.CompareYearMonth(DateTime.MaxValue, selectedDate.Value) > 0)
+                        {
+                            // since DisplayDate is not equal to
+                            // DateTime.MaxValue we are sure selectedDate is\
+                            // not null
+                            selectedDate = DateTimeHelper.AddMonths(selectedDate.Value, 1)!.Value;
+                            selectedDate = DateTimeHelper.AddDays(selectedDate.Value, -1)!.Value;
                         }
+                        else
+                        {
+                            selectedDate = DateTime.MaxValue;
+                        }
+                        ProcessSelection(shift, selectedDate, null);
                         break;
                     }
                 case CalendarMode.Year:
@@ -2026,7 +2020,6 @@ namespace Avalonia.Controls
                             focusDate = DisplayDate;
                             LastSelectedDate = DisplayDate;
                         }
-                        Debug.Assert(focusDate != null, "focusDate should not be null!");
                         FocusButton = FindDayButtonFromDay(focusDate);
 
                         if (FocusButton != null)
@@ -2091,17 +2084,17 @@ namespace Avalonia.Controls
 
         static Calendar()
         {
-            IsEnabledProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnIsEnabledChanged(e));
-            FirstDayOfWeekProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnFirstDayOfWeekChanged(e));
-            IsTodayHighlightedProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnIsTodayHighlightedChanged(e));
-            DisplayModeProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnDisplayModePropertyChanged(e));
-            SelectionModeProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnSelectionModeChanged(e));
-            SelectedDateProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnSelectedDateChanged(e));
-            DisplayDateProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnDisplayDateChanged(e));
-            DisplayDateStartProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnDisplayDateStartChanged(e));
-            DisplayDateEndProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnDisplayDateEndChanged(e));
-            KeyDownEvent.AddClassHandler<Calendar>((x,e) => x.Calendar_KeyDown(e));
-            KeyUpEvent.AddClassHandler<Calendar>((x,e) => x.Calendar_KeyUp(e));
+            IsEnabledProperty.Changed.AddClassHandler<Calendar>((x, e) => x.OnIsEnabledChanged(e));
+            FirstDayOfWeekProperty.Changed.AddClassHandler<Calendar>((x, e) => x.OnFirstDayOfWeekChanged(e));
+            IsTodayHighlightedProperty.Changed.AddClassHandler<Calendar>((x, e) => x.OnIsTodayHighlightedChanged(e));
+            DisplayModeProperty.Changed.AddClassHandler<Calendar>((x, e) => x.OnDisplayModePropertyChanged(e));
+            SelectionModeProperty.Changed.AddClassHandler<Calendar>((x, e) => x.OnSelectionModeChanged(e));
+            SelectedDateProperty.Changed.AddClassHandler<Calendar>((x, e) => x.OnSelectedDateChanged(e));
+            DisplayDateProperty.Changed.AddClassHandler<Calendar>((x, e) => x.OnDisplayDateChanged(e));
+            DisplayDateStartProperty.Changed.AddClassHandler<Calendar>((x, e) => x.OnDisplayDateStartChanged(e));
+            DisplayDateEndProperty.Changed.AddClassHandler<Calendar>((x, e) => x.OnDisplayDateEndChanged(e));
+            KeyDownEvent.AddClassHandler<Calendar>((x, e) => x.Calendar_KeyDown(e));
+            KeyUpEvent.AddClassHandler<Calendar>((x, e) => x.Calendar_KeyUp(e));
         }
 
         /// <summary>

src/Avalonia.Controls/Calendar/CalendarItem.cs

@@ -4,7 +4,6 @@
 // All other rights reserved.
 
 using System;
-using System.Collections.Generic;
 using System.Diagnostics;
 using System.Globalization;
 using Avalonia.Collections.Pooled;
@@ -353,7 +352,6 @@ namespace Avalonia.Controls.Primitives
         {
             if (Owner != null)
             {
-                Debug.Assert(Owner.DisplayDate != null, "The Owner Calendar's DisplayDate should not be null!");
                 _currentMonth = Owner.DisplayDateInternal;
             }
             else
@@ -361,17 +359,14 @@ namespace Avalonia.Controls.Primitives
                 _currentMonth = DateTime.Today;
             }
 
-            if (_currentMonth != null)
-            {
-                SetMonthModeHeaderButton();
-                SetMonthModePreviousButton(_currentMonth);
-                SetMonthModeNextButton(_currentMonth);
+            SetMonthModeHeaderButton();
+            SetMonthModePreviousButton(_currentMonth);
+            SetMonthModeNextButton(_currentMonth);
 
-                if (MonthView != null)
-                {
-                    SetDayTitles();
-                    SetCalendarDayButtons(_currentMonth);
-                }
+            if (MonthView != null)
+            {
+                SetDayTitles();
+                SetCalendarDayButtons(_currentMonth);
             }
         }
         private void SetMonthModeHeaderButton()
@@ -592,7 +587,6 @@ namespace Avalonia.Controls.Primitives
         {
             if (Owner != null)
             {
-                Debug.Assert(Owner.SelectedMonth != null, "The Owner Calendar's SelectedMonth should not be null!");
                 _currentMonth = (DateTime)Owner.SelectedMonth;
             }
             else
@@ -600,16 +594,13 @@ namespace Avalonia.Controls.Primitives
                 _currentMonth = DateTime.Today;
             }
 
-            if (_currentMonth != null)
-            {
-                SetYearModeHeaderButton();
-                SetYearModePreviousButton();
-                SetYearModeNextButton();
+            SetYearModeHeaderButton();
+            SetYearModePreviousButton();
+            SetYearModeNextButton();
 
-                if (YearView != null)
-                {
-                    SetMonthButtonsForYearMode();
-                }
+            if (YearView != null)
+            {
+                SetMonthButtonsForYearMode();
             }
         }
         private void SetYearModeHeaderButton()
@@ -660,7 +651,6 @@ namespace Avalonia.Controls.Primitives
                         childButton.IsCalendarButtonFocused = false;
                     }
 
-                    Debug.Assert(Owner.DisplayDateInternal != null, "The Owner Calendar's DisplayDateInternal should not be null!");
                     childButton.IsSelected = (DateTimeHelper.CompareYearMonth(day, Owner.DisplayDateInternal) == 0);
 
                     if (DateTimeHelper.CompareYearMonth(day, Owner.DisplayDateRangeStart) < 0 || DateTimeHelper.CompareYearMonth(day, Owner.DisplayDateRangeEnd) > 0)
@@ -685,7 +675,6 @@ namespace Avalonia.Controls.Primitives
 
             if (Owner != null)
             {
-                Debug.Assert(Owner.SelectedYear != null, "The owning Calendar's selected year should not be null!");
                 selectedYear = Owner.SelectedYear;
                 _currentMonth = (DateTime)Owner.SelectedMonth;
             }
@@ -695,19 +684,16 @@ namespace Avalonia.Controls.Primitives
                 selectedYear = DateTime.Today;
             }
 
-            if (_currentMonth != null)
-            {
-                int decade = DateTimeHelper.DecadeOfDate(selectedYear);
-                int decadeEnd = DateTimeHelper.EndOfDecade(selectedYear);
+            int decade = DateTimeHelper.DecadeOfDate(selectedYear);
+            int decadeEnd = DateTimeHelper.EndOfDecade(selectedYear);
 
-                SetDecadeModeHeaderButton(decade, decadeEnd);
-                SetDecadeModePreviousButton(decade);
-                SetDecadeModeNextButton(decadeEnd);
+            SetDecadeModeHeaderButton(decade, decadeEnd);
+            SetDecadeModePreviousButton(decade);
+            SetDecadeModeNextButton(decadeEnd);
 
-                if (YearView != null)
-                {
-                    SetYearButtons(decade, decadeEnd);
-                }
+            if (YearView != null)
+            {
+                SetYearButtons(decade, decadeEnd);
             }
         }
         internal void UpdateYearViewSelection(CalendarButton calendarButton)
@@ -822,22 +808,15 @@ namespace Avalonia.Controls.Primitives
                 {
                     if (Owner.DisplayMode == CalendarMode.Month)
                     {
-                        if (Owner.DisplayDate != null)
-                        {
-                            d = Owner.DisplayDateInternal;
-                            Owner.SelectedMonth = new DateTime(d.Year, d.Month, 1);
-                        }
+                        d = Owner.DisplayDateInternal;
+                        Owner.SelectedMonth = new DateTime(d.Year, d.Month, 1);
                         Owner.DisplayMode = CalendarMode.Year;
                     }
                     else
                     {
                         Debug.Assert(Owner.DisplayMode == CalendarMode.Year, "The Owner Calendar's DisplayMode should be Year!");
-
-                        if (Owner.SelectedMonth != null)
-                        {
-                            d = Owner.SelectedMonth;
-                            Owner.SelectedYear = new DateTime(d.Year, d.Month, 1);
-                        }
+                        d = Owner.SelectedMonth;
+                        Owner.SelectedYear = new DateTime(d.Year, d.Month, 1);
                         Owner.DisplayMode = CalendarMode.Decade;
                     }
                 }

src/Avalonia.Controls/Calendar/SelectedDatesCollection.cs

@@ -297,7 +297,7 @@ namespace Avalonia.Controls.Primitives
                 }
                 else
                 {
-                    if (item != null && DateTime.Compare(this[index], item) != 0 && Calendar.IsValidDateSelection(_owner, item))
+                    if (DateTime.Compare(this[index], item) != 0 && Calendar.IsValidDateSelection(_owner, item))
                     {
                         removedItems.Add(this[index]);
                         base.SetItem(index, item);

src/Avalonia.Controls/GridLength.cs

@@ -180,7 +180,7 @@ namespace Avalonia.Controls
                 return "Auto";
             }
 
-            string s = _value.ToString();
+            string s = _value.ToString(CultureInfo.InvariantCulture);
             return IsStar ? s + "*" : s;
         }
 

src/Avalonia.Controls/Platform/InternalPlatformThreadingInterface.cs

@@ -43,7 +43,7 @@ namespace Avalonia.Controls.Platform
                 _priority = priority;
                 _interval = interval;
                 _tick = tick;
-                _timer = new Timer(OnTimer, null, interval, TimeSpan.FromMilliseconds(-1));
+                _timer = new Timer(OnTimer, null, interval, Timeout.InfiniteTimeSpan);
                 _handle = GCHandle.Alloc(_timer);
             }
 
@@ -57,7 +57,7 @@ namespace Avalonia.Controls.Platform
                     if (_timer == null)
                         return;
                     _tick();
-                    _timer?.Change(_interval, TimeSpan.FromMilliseconds(-1));
+                    _timer?.Change(_interval, Timeout.InfiniteTimeSpan);
                 });
             }
 

src/Avalonia.Controls/Shapes/Arc.cs

@@ -1,8 +1,12 @@
 using System;
 using Avalonia.Media;
+using Avalonia.Utilities;
 
 namespace Avalonia.Controls.Shapes
 {
+    /// <summary>
+    /// Represents a circular or elliptical arc (a segment of a curve).
+    /// </summary>
     public class Arc : Shape
     {
         /// <summary>
@@ -19,8 +23,12 @@ namespace Avalonia.Controls.Shapes
 
         static Arc()
         {
-            StrokeThicknessProperty.OverrideDefaultValue<Arc>(1);
-            AffectsGeometry<Arc>(BoundsProperty, StrokeThicknessProperty, StartAngleProperty, SweepAngleProperty);
+            StrokeThicknessProperty.OverrideDefaultValue<Arc>(1.0d);
+            AffectsGeometry<Arc>(
+                BoundsProperty,
+                StrokeThicknessProperty,
+                StartAngleProperty,
+                SweepAngleProperty);
         }
 
         /// <summary>
@@ -42,10 +50,11 @@ namespace Avalonia.Controls.Shapes
             set => SetValue(SweepAngleProperty, value);
         }
 
+        /// <inheritdoc/>
         protected override Geometry CreateDefiningGeometry()
         {
-            var angle1 = DegreesToRad(StartAngle);
-            var angle2 = angle1 + DegreesToRad(SweepAngle);
+            var angle1 = MathUtilities.Deg2Rad(StartAngle);
+            var angle2 = angle1 + MathUtilities.Deg2Rad(SweepAngle);
 
             var startAngle = Math.Min(angle1, angle2);
             var sweepAngle = Math.Max(angle1, angle2);
@@ -80,24 +89,25 @@ namespace Avalonia.Controls.Shapes
 
                 var arcGeometry = new StreamGeometry();
 
-                using (var ctx = arcGeometry.Open())
+                using (StreamGeometryContext context = arcGeometry.Open())
                 {
-                    ctx.BeginFigure(startPoint, false);
-                    ctx.ArcTo(endPoint, new Size(radiusX, radiusY), angleGap, angleGap >= Math.PI,
+                    context.BeginFigure(startPoint, false);
+                    context.ArcTo(
+                        endPoint,
+                        new Size(radiusX, radiusY),
+                        rotationAngle: angleGap,
+                        isLargeArc: angleGap >= Math.PI,
                         SweepDirection.Clockwise);
-                    ctx.EndFigure(false);
+                    context.EndFigure(false);
                 }
 
                 return arcGeometry;
             }
         }
 
-        static double DegreesToRad(double inAngle) =>
-            inAngle * Math.PI / 180;
+        private static double RadToNormRad(double inAngle) => ((inAngle % (Math.PI * 2)) + (Math.PI * 2)) % (Math.PI * 2);
 
-        static double RadToNormRad(double inAngle) => ((inAngle % (Math.PI * 2)) + (Math.PI * 2)) % (Math.PI * 2);
-
-        static Point GetRingPoint(double radiusX, double radiusY, double centerX, double centerY, double angle) =>
+        private static Point GetRingPoint(double radiusX, double radiusY, double centerX, double centerY, double angle) =>
             new Point((radiusX * Math.Cos(angle)) + centerX, (radiusY * Math.Sin(angle)) + centerY);
     }
 }

src/Avalonia.Controls/Shapes/Sector.cs

@@ -0,0 +1,97 @@
+using System;
+using Avalonia.Media;
+using Avalonia.Utilities;
+
+namespace Avalonia.Controls.Shapes
+{
+    /// <summary>
+    /// Represents a circular or elliptical sector (a pie-shaped closed region of a circle or ellipse).
+    /// </summary>
+    public class Sector : Shape
+    {
+        /// <summary>
+        /// Defines the <see cref="StartAngle"/> property.
+        /// </summary>
+        public static readonly StyledProperty<double> StartAngleProperty =
+            AvaloniaProperty.Register<Sector, double>(nameof(StartAngle), 0.0d);
+
+        /// <summary>
+        /// Defines the <see cref="SweepAngle"/> property.
+        /// </summary>
+        public static readonly StyledProperty<double> SweepAngleProperty =
+            AvaloniaProperty.Register<Sector, double>(nameof(SweepAngle), 0.0d);
+
+        /// <summary>
+        /// Gets or sets the angle at which the sector's arc starts, in degrees.
+        /// </summary>
+        public double StartAngle
+        {
+            get => GetValue(StartAngleProperty);
+            set => SetValue(StartAngleProperty, value);
+        }
+
+        /// <summary>
+        /// Gets or sets the angle, in degrees, added to the <see cref="StartAngle"/> defining where the sector's arc ends.
+        /// A positive value is clockwise, negative is counter-clockwise.
+        /// </summary>
+        public double SweepAngle
+        {
+            get => GetValue(SweepAngleProperty);
+            set => SetValue(SweepAngleProperty, value);
+        }
+
+        static Sector()
+        {
+            StrokeThicknessProperty.OverrideDefaultValue<Sector>(1.0d);
+            AffectsGeometry<Sector>(
+                BoundsProperty,
+                StrokeThicknessProperty,
+                StartAngleProperty,
+                SweepAngleProperty);
+        }
+
+        /// <inheritdoc/>
+        protected override Geometry? CreateDefiningGeometry()
+        {
+            Rect rect = new Rect(Bounds.Size);
+            Rect deflatedRect = rect.Deflate(StrokeThickness * 0.5d);
+
+            if (SweepAngle >= 360.0d || SweepAngle <= -360.0d)
+            {
+                return new EllipseGeometry(deflatedRect);
+            }
+
+            if (SweepAngle == 0.0d)
+            {
+                return new StreamGeometry();
+            }
+
+            (double startAngle, double endAngle) = MathUtilities.GetMinMaxFromDelta(
+                MathUtilities.Deg2Rad(StartAngle),
+                MathUtilities.Deg2Rad(SweepAngle));
+
+            Point centre = new Point(rect.Width * 0.5d, rect.Height * 0.5d);
+            double radiusX = deflatedRect.Width * 0.5d;
+            double radiusY = deflatedRect.Height * 0.5d;
+            Point startCurvePoint = MathUtilities.GetEllipsePoint(centre, radiusX, radiusY, startAngle);
+            Point endCurvePoint = MathUtilities.GetEllipsePoint(centre, radiusX, radiusY, endAngle);
+            Size size = new Size(radiusX, radiusY);
+
+            var streamGeometry = new StreamGeometry();
+            using (StreamGeometryContext context = streamGeometry.Open())
+            {
+                context.BeginFigure(startCurvePoint, false);
+                context.ArcTo(
+                    endCurvePoint,
+                    size,
+                    rotationAngle: 0.0d,
+                    isLargeArc: Math.Abs(SweepAngle) > 180.0d,
+                    SweepDirection.Clockwise);
+                context.LineTo(centre);
+                context.EndFigure(true);
+            }
+
+            return streamGeometry;
+        }
+    }
+}

src/Avalonia.Headless/HeadlessPlatformThreadingInterface.cs

@@ -36,35 +36,35 @@ namespace Avalonia.Headless
 
         public IDisposable StartTimer(DispatcherPriority priority, TimeSpan interval, Action tick)
         {
-            var cancelled = false;
-            var enqueued = false;
-            var l = new object();
-            var timer = new Timer(_ =>
+            if (interval.TotalMilliseconds < 10)
+                interval = TimeSpan.FromMilliseconds(10);
+
+            var stopped = false;
+            Timer timer = null;
+            timer = new Timer(_ =>
             {
-                lock (l)
+                if (stopped)
+                    return;
+
+                Dispatcher.UIThread.Post(() =>
                 {
-                    if (cancelled || enqueued)
-                        return;
-                    enqueued = true;
-                    Dispatcher.UIThread.Post(() =>
+                    try
                     {
-                        lock (l)
-                        {
-                            enqueued = false;
-                            if (cancelled)
-                                return;
-                            tick();
-                        }
-                    }, priority);
-                }
-            }, null, interval, interval);
+                        tick();
+                    }
+                    finally
+                    {
+                        if (!stopped)
+                            timer.Change(interval, Timeout.InfiniteTimeSpan);
+                    }
+                });
+            },
+            null, interval, Timeout.InfiniteTimeSpan);
+
             return Disposable.Create(() =>
             {
-                lock (l)
-                {
-                    timer.Dispose();
-                    cancelled = true;
-                }
+                stopped = true;
+                timer.Dispose();
             });
         }
 

src/Avalonia.OpenGL/Controls/OpenGlControlBase.cs

@@ -34,7 +34,7 @@ namespace Avalonia.OpenGL.Controls
                 _attachment.Present();
             }
 
-            context.DrawImage(_bitmap, new Rect(_bitmap.Size), Bounds);
+            context.DrawImage(_bitmap, new Rect(_bitmap.Size), new Rect(Bounds.Size));
             base.Render(context);
         }
         
@@ -84,6 +84,7 @@ namespace Avalonia.OpenGL.Controls
                 using (_context.MakeCurrent())
                 {
                     var gl = _context.GlInterface;
+                    gl.ActiveTexture(GL_TEXTURE0);
                     gl.BindTexture(GL_TEXTURE_2D, 0);
                     gl.BindFramebuffer(GL_FRAMEBUFFER, 0);
                     gl.DeleteFramebuffer(_fb);

src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/Transformers/AvaloniaXamlIlDeferredResourceTransformer.cs

@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.Linq;
 using XamlX.Ast;
 using XamlX.Emit;
@@ -47,7 +48,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
             return !node.Type.GetClrType().IsValueType;
         }
         
-        class AdderSetter : IXamlPropertySetter, IXamlEmitablePropertySetter<IXamlILEmitter>
+        class AdderSetter : IXamlILOptimizedEmitablePropertySetter, IEquatable<AdderSetter>
         {
             private readonly IXamlMethod _getter;
             private readonly IXamlMethod _adder;
@@ -58,16 +59,22 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
                 _adder = adder;
                 TargetType = getter.DeclaringType;
                 Parameters = adder.ParametersWithThis().Skip(1).ToList();
+
+                bool allowNull = Parameters.Last().AcceptsNull();
+                BinderParameters = new PropertySetterBinderParameters
+                {
+                    AllowMultiple = true,
+                    AllowXNull = allowNull,
+                    AllowRuntimeNull = allowNull
+                };
             }
 
             public IXamlType TargetType { get; }
 
-            public PropertySetterBinderParameters BinderParameters { get; } = new PropertySetterBinderParameters
-            {
-                AllowMultiple = true
-            };
+            public PropertySetterBinderParameters BinderParameters { get; }
 
             public IReadOnlyList<IXamlType> Parameters { get; }
+
             public void Emit(IXamlILEmitter emitter)
             {
                 var locals = new Stack<XamlLocalsPool.PooledLocal>();
@@ -80,11 +87,40 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
                 }
 
                 emitter.EmitCall(_getter);
-                while (locals.Count > 0)
+                while (locals.Count>0)
                     using (var loc = locals.Pop())
                         emitter.Ldloc(loc.Local);
                 emitter.EmitCall(_adder, true);
             }
+
+            public void EmitWithArguments(
+                XamlEmitContextWithLocals<IXamlILEmitter, XamlILNodeEmitResult> context,
+                IXamlILEmitter emitter,
+                IReadOnlyList<IXamlAstValueNode> arguments)
+            {
+                emitter.EmitCall(_getter);
+
+                for (var i = 0; i < arguments.Count; ++i)
+                    context.Emit(arguments[i], emitter, Parameters[i]);
+
+                emitter.EmitCall(_adder, true);
+            }
+
+            public bool Equals(AdderSetter other)
+            {
+                if (ReferenceEquals(null, other))
+                    return false;
+                if (ReferenceEquals(this, other))
+                    return true;
+
+                return _getter.Equals(other._getter) && _adder.Equals(other._adder);
+            }
+
+            public override bool Equals(object obj)
+                => Equals(obj as AdderSetter);
+
+            public override int GetHashCode()
+                => (_getter.GetHashCode() * 397) ^ _adder.GetHashCode();
         }
     }
 }

src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/Transformers/AvaloniaXamlIlSetterTransformer.cs

@@ -75,17 +75,17 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
             {
                 Getter = setterType.Methods.First(m => m.Name == "get_Value");
                 var method = setterType.Methods.First(m => m.Name == "set_Value");
-                Setters.Add(new XamlIlDirectCallPropertySetter(method, types.IBinding));
-                Setters.Add(new XamlIlDirectCallPropertySetter(method, types.UnsetValueType));
-                Setters.Add(new XamlIlDirectCallPropertySetter(method, targetType));
+                Setters.Add(new XamlIlDirectCallPropertySetter(method, types.IBinding, false));
+                Setters.Add(new XamlIlDirectCallPropertySetter(method, types.UnsetValueType, false));
+                Setters.Add(new XamlIlDirectCallPropertySetter(method, targetType, targetType.AcceptsNull()));
             }
             
-            class XamlIlDirectCallPropertySetter : IXamlPropertySetter, IXamlEmitablePropertySetter<IXamlILEmitter>
+            sealed class XamlIlDirectCallPropertySetter : IXamlPropertySetter, IXamlEmitablePropertySetter<IXamlILEmitter>
             {
                 private readonly IXamlMethod _method;
                 private readonly IXamlType _type;
                 public IXamlType TargetType { get; }
-                public PropertySetterBinderParameters BinderParameters { get; } = new PropertySetterBinderParameters();
+                public PropertySetterBinderParameters BinderParameters { get; }
                 public IReadOnlyList<IXamlType> Parameters { get; }
                 public void Emit(IXamlILEmitter codegen)
                 {
@@ -94,13 +94,27 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
                     codegen.EmitCall(_method, true);
                 }
 
-                public XamlIlDirectCallPropertySetter(IXamlMethod method, IXamlType type)
+                public XamlIlDirectCallPropertySetter(IXamlMethod method, IXamlType type, bool allowNull)
                 {
                     _method = method;
                     _type = type;
                     Parameters = new[] {type};
                     TargetType = method.ThisOrFirstParameter();
+                    BinderParameters = new PropertySetterBinderParameters
+                    {
+                        AllowXNull = allowNull,
+                        AllowRuntimeNull = allowNull
+                    };
                 }
+
+                private bool Equals(XamlIlDirectCallPropertySetter other) 
+                    => Equals(_method, other._method) && Equals(_type, other._type);
+
+                public override bool Equals(object obj) 
+                    => Equals(obj as XamlIlDirectCallPropertySetter);
+
+                public override int GetHashCode() 
+                    => (_method.GetHashCode() * 397) ^ _type.GetHashCode();
             }
         }
     }

src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/XamlIlAvaloniaPropertyHelper.cs

@@ -206,38 +206,64 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
             Setters.Insert(0, new UnsetValueSetter(types, original.DeclaringType, field));
         }
 
-        abstract class AvaloniaPropertyCustomSetter : IXamlPropertySetter, IXamlEmitablePropertySetter<IXamlILEmitter>
+        abstract class AvaloniaPropertyCustomSetter : IXamlILOptimizedEmitablePropertySetter, IEquatable<AvaloniaPropertyCustomSetter>
         {
-            protected AvaloniaXamlIlWellKnownTypes Types;
-            protected IXamlField AvaloniaProperty;
+            protected readonly AvaloniaXamlIlWellKnownTypes Types;
+            protected readonly IXamlField AvaloniaProperty;
 
-            public AvaloniaPropertyCustomSetter(AvaloniaXamlIlWellKnownTypes types,
+            protected AvaloniaPropertyCustomSetter(
+                AvaloniaXamlIlWellKnownTypes types,
                 IXamlType declaringType,
-                IXamlField avaloniaProperty)
+                IXamlField avaloniaProperty,
+                bool allowNull)
             {
                 Types = types;
                 AvaloniaProperty = avaloniaProperty;
                 TargetType = declaringType;
+                BinderParameters = new PropertySetterBinderParameters
+                {
+                    AllowXNull = allowNull,
+                    AllowRuntimeNull = allowNull
+                };
             }
 
             public IXamlType TargetType { get; }
 
-            public PropertySetterBinderParameters BinderParameters { get; } = new PropertySetterBinderParameters
-            {
-                AllowXNull = false
-            };
+            public PropertySetterBinderParameters BinderParameters { get; }
 
             public IReadOnlyList<IXamlType> Parameters { get; set; }
-            public abstract void Emit(IXamlILEmitter codegen);
+
+            public abstract void Emit(IXamlILEmitter emitter);
+
+            public abstract void EmitWithArguments(
+                XamlEmitContextWithLocals<IXamlILEmitter, XamlILNodeEmitResult> context,
+                IXamlILEmitter emitter,
+                IReadOnlyList<IXamlAstValueNode> arguments);
+
+            public bool Equals(AvaloniaPropertyCustomSetter other)
+            {
+                if (ReferenceEquals(null, other))
+                    return false;
+                if (ReferenceEquals(this, other))
+                    return true;
+
+                return GetType() == other.GetType() && AvaloniaProperty.Equals(other.AvaloniaProperty);
+            }
+
+            public override bool Equals(object obj)
+                => Equals(obj as AvaloniaPropertyCustomSetter);
+
+            public override int GetHashCode() 
+                => AvaloniaProperty.GetHashCode();
         }
 
         class BindingSetter : AvaloniaPropertyCustomSetter
         {
             public BindingSetter(AvaloniaXamlIlWellKnownTypes types,
                 IXamlType declaringType,
-                IXamlField avaloniaProperty) : base(types, declaringType, avaloniaProperty)
+                IXamlField avaloniaProperty) : base(types, declaringType, avaloniaProperty, false)
             {
-                Parameters = new[] {types.IBinding};
+                Parameters = new[] { types.IBinding };
             }
 
             public override void Emit(IXamlILEmitter emitter)
@@ -246,10 +272,25 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
                     emitter
                         .Stloc(bloc.Local)
                         .Ldsfld(AvaloniaProperty)
-                        .Ldloc(bloc.Local)
-                        // TODO: provide anchor?
-                        .Ldnull();
-                emitter.EmitCall(Types.AvaloniaObjectBindMethod, true);
+                        .Ldloc(bloc.Local);
+                EmitAnchorAndBind(emitter);
+            }
+
+            public override void EmitWithArguments(
+                XamlEmitContextWithLocals<IXamlILEmitter, XamlILNodeEmitResult> context,
+                IXamlILEmitter emitter,
+                IReadOnlyList<IXamlAstValueNode> arguments)
+            {
+                emitter.Ldsfld(AvaloniaProperty);
+                context.Emit(arguments[0], emitter, Parameters[0]);
+                EmitAnchorAndBind(emitter);
+            }
+
+            private void EmitAnchorAndBind(IXamlILEmitter emitter)
+            {
+                emitter
+                    .Ldnull() // TODO: provide anchor?
+                    .EmitCall(Types.AvaloniaObjectBindMethod, true);
             }
         }
 
@@ -257,7 +298,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
         {
             public BindingWithPrioritySetter(AvaloniaXamlIlWellKnownTypes types,
                 IXamlType declaringType,
-                IXamlField avaloniaProperty) : base(types, declaringType, avaloniaProperty)
+                IXamlField avaloniaProperty) : base(types, declaringType, avaloniaProperty, false)
             {
                 Parameters = new[] { types.BindingPriority, types.IBinding };
             }
@@ -265,15 +306,29 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
             public override void Emit(IXamlILEmitter emitter)
             {
                 using (var bloc = emitter.LocalsPool.GetLocal(Types.IBinding))
-                using (var priorityLocal = emitter.LocalsPool.GetLocal(Types.Int))
                     emitter
                         .Stloc(bloc.Local)
-                        .Stloc(priorityLocal.Local)
+                        .Pop() // ignore priority
                         .Ldsfld(AvaloniaProperty)
-                        .Ldloc(bloc.Local)
-                        // TODO: provide anchor?
-                        .Ldnull();
-                emitter.EmitCall(Types.AvaloniaObjectBindMethod, true);
+                        .Ldloc(bloc.Local);
+                EmitAnchorAndBind(emitter);
+            }
+
+            public override void EmitWithArguments(
+                XamlEmitContextWithLocals<IXamlILEmitter, XamlILNodeEmitResult> context,
+                IXamlILEmitter emitter,
+                IReadOnlyList<IXamlAstValueNode> arguments)
+            {
+                emitter.Ldsfld(AvaloniaProperty);
+                context.Emit(arguments[1], emitter, Parameters[1]);
+                EmitAnchorAndBind(emitter);
+            }
+
+            private void EmitAnchorAndBind(IXamlILEmitter emitter)
+            {
+                emitter
+                    .Ldnull() // TODO: provide anchor?
+                    .EmitCall(Types.AvaloniaObjectBindMethod, true);
             }
         }
 
@@ -281,7 +336,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
         {
             public SetValueWithPrioritySetter(AvaloniaXamlIlWellKnownTypes types, IXamlType declaringType, IXamlField avaloniaProperty,
                 IXamlType propertyType)
-                : base(types, declaringType, avaloniaProperty)
+                : base(types, declaringType, avaloniaProperty, propertyType.AcceptsNull())
             {
                 Parameters = new[] { types.BindingPriority, propertyType };
             }
@@ -295,9 +350,6 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
                    - value
                 */
 
-                var method = Types.AvaloniaObjectSetStyledPropertyValue
-                    .MakeGenericMethod(new[] { Parameters[1] });
-
                 using (var valueLocal = emitter.LocalsPool.GetLocal(Parameters[1]))
                 using (var priorityLocal = emitter.LocalsPool.GetLocal(Types.Int))
                     emitter
@@ -305,25 +357,57 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
                         .Stloc(priorityLocal.Local)
                         .Ldsfld(AvaloniaProperty)
                         .Ldloc(valueLocal.Local)
-                        .Ldloc(priorityLocal.Local)
-                        .EmitCall(method, true);
+                        .Ldloc(priorityLocal.Local);
+
+                EmitSetStyledPropertyValue(emitter);
+            }
+
+            public override void EmitWithArguments(
+                XamlEmitContextWithLocals<IXamlILEmitter, XamlILNodeEmitResult> context,
+                IXamlILEmitter emitter,
+                IReadOnlyList<IXamlAstValueNode> arguments)
+            {
+                emitter.Ldsfld(AvaloniaProperty);
+                context.Emit(arguments[1], emitter, Parameters[1]);
+                context.Emit(arguments[0], emitter, Parameters[0]);
+                EmitSetStyledPropertyValue(emitter);
+            }
+
+            private void EmitSetStyledPropertyValue(IXamlILEmitter emitter)
+            {
+                var method = Types.AvaloniaObjectSetStyledPropertyValue.MakeGenericMethod(new[] { Parameters[1] });
+                emitter.EmitCall(method, true);
             }
         }
 
         class UnsetValueSetter : AvaloniaPropertyCustomSetter
         {
             public UnsetValueSetter(AvaloniaXamlIlWellKnownTypes types, IXamlType declaringType, IXamlField avaloniaProperty) 
-                : base(types, declaringType, avaloniaProperty)
+                : base(types, declaringType, avaloniaProperty, false)
             {
-                Parameters = new[] {types.UnsetValueType};
+                Parameters = new[] { types.UnsetValueType };
             }
 
             public override void Emit(IXamlILEmitter codegen)
             {
+                codegen.Pop();
+                EmitSetValue(codegen);
+            }
+
+            public override void EmitWithArguments(
+                XamlEmitContextWithLocals<IXamlILEmitter, XamlILNodeEmitResult> context,
+                IXamlILEmitter emitter,
+                IReadOnlyList<IXamlAstValueNode> arguments)
+            {
+                EmitSetValue(emitter);
+            }
+
+            private void EmitSetValue(IXamlILEmitter emitter)
+            {
+                // Ignore the instance and load one from the static field to avoid extra local variable
                 var unsetValue = Types.AvaloniaProperty.Fields.First(f => f.Name == "UnsetValue");
-                codegen
-                    // Ignore the instance and load one from the static field to avoid extra local variable
-                    .Pop()
+
+                emitter
                     .Ldsfld(AvaloniaProperty)
                     .Ldsfld(unsetValue)
                     .Ldc_I4(0)

src/Markup/Avalonia.Markup.Xaml.Loader/xamlil.github

@@ -1 +1 @@
-Subproject commit a4e6be2d1407abec4f35fcb208848830ce513ead
+Subproject commit c1c0594ec2c35b08988183b1a5b3e34dfa19179d

src/Skia/Avalonia.Skia/Gpu/OpenGl/OpenGlBitmapImpl.cs

@@ -41,7 +41,7 @@ namespace Avalonia.Skia
                         new GRGlTextureInfo(
                             GlConsts.GL_TEXTURE_2D, (uint)_surface.GetTextureId(),
                             (uint)_surface.InternalFormat)))
-                    using (var surface = SKSurface.Create(context.GrContext, backendTexture, GRSurfaceOrigin.TopLeft,
+                    using (var surface = SKSurface.Create(context.GrContext, backendTexture, GRSurfaceOrigin.BottomLeft,
                         SKColorType.Rgba8888))
                     {
                         // Again, silently ignore, if something went wrong it's not our fault
@@ -118,7 +118,7 @@ namespace Avalonia.Skia
                 {
                     var gl = _context.GlInterface;
                     
-                    var textures = new int[2];
+                    Span<int> textures = stackalloc int[2];
                     fixed (int* ptex = textures)
                         gl.GenTextures(2, ptex);
                     _texture = textures[0];
@@ -139,7 +139,6 @@ namespace Avalonia.Skia
 
                     gl.FramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, _texture, 0);
                     gl.BindTexture(GL_TEXTURE_2D, oldTexture);
-                    
                 }
             }
         }
@@ -161,15 +160,15 @@ namespace Avalonia.Skia
                     gl.GetIntegerv(GL_ACTIVE_TEXTURE, out var oldActive);
                     
                     gl.BindFramebuffer(GL_FRAMEBUFFER, _fbo);
-                    gl.BindTexture(GL_TEXTURE_2D, _frontBuffer);
                     gl.ActiveTexture(GL_TEXTURE0);
+                    gl.BindTexture(GL_TEXTURE_2D, _frontBuffer);
 
                     gl.CopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, _bitmap.PixelSize.Width,
                         _bitmap.PixelSize.Height);
 
                     gl.BindFramebuffer(GL_FRAMEBUFFER, oldFbo);
-                    gl.BindTexture(GL_TEXTURE_2D, oldTexture);
                     gl.ActiveTexture(oldActive);
+                    gl.BindTexture(GL_TEXTURE_2D, oldTexture);
                     
                     gl.Finish();
                 }
@@ -192,9 +191,8 @@ namespace Avalonia.Skia
                 if(_disposed)
                     return;
                 _disposed = true;
-                var tex = new[] { _texture, _frontBuffer };
-                fixed (int* ptex = tex)
-                    gl.DeleteTextures(2, ptex);
+                var ptex = stackalloc[] { _texture, _frontBuffer };
+                gl.DeleteTextures(2, ptex);
             }
         }
 

src/Windows/Avalonia.Win32/WindowImpl.cs

@@ -285,11 +285,12 @@ namespace Avalonia.Win32
 
             set
             {
-                if (IsWindowVisible(_hwnd))
+                if (IsWindowVisible(_hwnd) && _lastWindowState != value)
                 {
                     ShowWindow(value, value != WindowState.Minimized); // If the window is minimized, it shouldn't be activated
                 }
 
+                _lastWindowState = value;
                 _showWindowState = value;
             }
         }

tests/Avalonia.Controls.UnitTests/GridLengthTests.cs

@@ -1,6 +1,8 @@
 using System;
+using System.Collections.Generic;
 using System.Globalization;
 using System.Linq;
+using System.Threading.Tasks;
 using Xunit;
 
 namespace Avalonia.Controls.UnitTests
@@ -100,5 +102,23 @@ namespace Avalonia.Controls.UnitTests
                 },
                 result);
         }
+
+        [Theory]
+        [InlineData(1.2d, GridUnitType.Pixel, "1.2")]
+        [InlineData(1.2d, GridUnitType.Star, "1.2*")]
+        [InlineData(1.2d, GridUnitType.Auto, "Auto")]
+        public async void ToString_AllCulture_Should_Pass(double d, GridUnitType type, string result)
+        {
+            List<CultureInfo> cultureInfos = CultureInfo.GetCultures(CultureTypes.AllCultures).ToList();
+            GridLength length = new GridLength(d, type);
+            foreach(var culture in cultureInfos)
+            {
+                await Task.Run(() =>
+                {
+                    CultureInfo.CurrentCulture = culture;
+                    Assert.Equal(result, length.ToString());
+                });
+            }
+        }
     }
 }

tests/Avalonia.IntegrationTests.Appium/WindowTests.cs

@@ -1,7 +1,9 @@
 using System;
+using System.Linq;
 using System.Runtime.InteropServices;
 using System.Threading;
 using Avalonia.Controls;
+using OpenQA.Selenium;
 using OpenQA.Selenium.Appium;
 using OpenQA.Selenium.Interactions;
 using Xunit;
@@ -55,6 +57,43 @@ namespace Avalonia.IntegrationTests.Appium
                 }
             }
         }
+        
+        [PlatformFact(TestPlatforms.Windows)]
+        public void OnWindows_Docked_Windows_Retain_Size_Position_When_Restored()
+        {
+            using (OpenWindow(new Size(400, 400), ShowWindowMode.NonOwned, WindowStartupLocation.Manual))
+            {
+                var windowState = _session.FindElementByAccessibilityId("WindowState");
+
+                Assert.Equal("Normal", windowState.GetComboBoxValue());
+                
+                
+                var window = _session.FindElements(By.XPath("//Window")).First();
+                
+                new Actions(_session)
+                    .KeyDown(Keys.Meta)
+                    .SendKeys(Keys.Left)
+                    .KeyUp(Keys.Meta)
+                    .Perform();
+                
+                var original = GetWindowInfo();
+                
+                windowState.Click();
+                _session.FindElementByName("Minimized").SendClick();
+                
+                new Actions(_session)
+                    .KeyDown(Keys.Alt)
+                    .SendKeys(Keys.Tab)
+                    .KeyUp(Keys.Alt)
+                    .Perform();
+                
+                var current = GetWindowInfo();
+                
+                Assert.Equal(original.Position, current.Position);
+                Assert.Equal(original.FrameSize, current.FrameSize);
+
+            }
+        }
 
 
         [Theory]
@@ -92,7 +131,8 @@ namespace Avalonia.IntegrationTests.Appium
                 Assert.True(clientSize.Width >= current.ScreenRect.Width);
                 Assert.True(clientSize.Height >= current.ScreenRect.Height);
 
-                windowState.Click();
+                windowState.SendClick();
+                
                 _session.FindElementByName("Normal").SendClick();
 
                 current = GetWindowInfo();

tests/Avalonia.IntegrationTests.Appium/WindowTests_MacOS.cs

@@ -211,6 +211,35 @@ namespace Avalonia.IntegrationTests.Appium
             }
         }
 
+        [PlatformFact(TestPlatforms.MacOS)]
+        public void Hidden_Child_Window_Is_Not_Reshown_When_Parent_Clicked()
+        {
+            var mainWindow = _session.FindElementByAccessibilityId("MainWindow");
+
+            // We don't use dispose to close the window here, because it seems that hiding and re-showing a window
+            // causes Appium to think it's a different window.
+            OpenWindow(null, ShowWindowMode.Owned, WindowStartupLocation.Manual);
+            
+            var secondaryWindow = FindWindow(_session, "SecondaryWindow");
+            var hideButton = secondaryWindow.FindElementByAccessibilityId("HideButton");
+
+            hideButton.Click();
+                
+            var windows = _session.FindElementsByXPath("XCUIElementTypeWindow");
+            Assert.Single(windows);
+                
+            mainWindow.Click();
+                
+            windows = _session.FindElementsByXPath("XCUIElementTypeWindow");
+            Assert.Single(windows);
+                
+            _session.FindElementByAccessibilityId("RestoreAll").Click();
+
+            // Close the window manually.
+            secondaryWindow = FindWindow(_session, "SecondaryWindow");
+            secondaryWindow.GetChromeButtons().close.Click();
+        }
+
         private IDisposable OpenWindow(PixelSize? size, ShowWindowMode mode, WindowStartupLocation location)
         {
             var sizeTextBox = _session.FindElementByAccessibilityId("ShowWindowSize");