Merge remote-tracking branch 'origin/refactor_pointerover_backportable' into Stylus

# Conflicts:
#	src/Avalonia.Input/MouseDevice.cs

Avalonia.sln

@@ -117,6 +117,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Props", "Props", "{F3AC8BC1
 		build\Base.props = build\Base.props
 		build\Binding.props = build\Binding.props
 		build\CoreLibraries.props = build\CoreLibraries.props
+		build\DevAnalyzers.props = build\DevAnalyzers.props
 		build\EmbedXaml.props = build\EmbedXaml.props
 		build\HarfBuzzSharp.props = build\HarfBuzzSharp.props
 		build\JetBrains.Annotations.props = build\JetBrains.Annotations.props
@@ -234,7 +235,9 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Avalonia.PlatformSupport",
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ControlCatalog.iOS", "samples\ControlCatalog.iOS\ControlCatalog.iOS.csproj", "{70B9F5CC-E2F9-4314-9514-EDE762ACCC4B}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Avalonia.PlatformSupport.UnitTests", "tests\Avalonia.PlatformSupport.UnitTests\Avalonia.PlatformSupport.UnitTests.csproj", "{CE910927-CE5A-456F-BC92-E4C757354A5C}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Avalonia.PlatformSupport.UnitTests", "tests\Avalonia.PlatformSupport.UnitTests\Avalonia.PlatformSupport.UnitTests.csproj", "{CE910927-CE5A-456F-BC92-E4C757354A5C}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "DevAnalyzers", "src\tools\DevAnalyzers\DevAnalyzers.csproj", "{2B390431-288C-435C-BB6B-A374033BD8D1}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -2238,6 +2241,30 @@ Global
 		{CE910927-CE5A-456F-BC92-E4C757354A5C}.Release|iPhone.Build.0 = Release|Any CPU
 		{CE910927-CE5A-456F-BC92-E4C757354A5C}.Release|iPhoneSimulator.ActiveCfg = Release|Any CPU
 		{CE910927-CE5A-456F-BC92-E4C757354A5C}.Release|iPhoneSimulator.Build.0 = Release|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Ad-Hoc|Any CPU.ActiveCfg = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Ad-Hoc|Any CPU.Build.0 = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Ad-Hoc|iPhone.ActiveCfg = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Ad-Hoc|iPhone.Build.0 = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Ad-Hoc|iPhoneSimulator.ActiveCfg = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Ad-Hoc|iPhoneSimulator.Build.0 = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.AppStore|Any CPU.ActiveCfg = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.AppStore|Any CPU.Build.0 = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.AppStore|iPhone.ActiveCfg = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.AppStore|iPhone.Build.0 = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.AppStore|iPhoneSimulator.ActiveCfg = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.AppStore|iPhoneSimulator.Build.0 = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Debug|iPhone.ActiveCfg = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Debug|iPhone.Build.0 = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Debug|iPhoneSimulator.ActiveCfg = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Debug|iPhoneSimulator.Build.0 = Debug|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Release|Any CPU.Build.0 = Release|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Release|iPhone.ActiveCfg = Release|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Release|iPhone.Build.0 = Release|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Release|iPhoneSimulator.ActiveCfg = Release|Any CPU
+		{2B390431-288C-435C-BB6B-A374033BD8D1}.Release|iPhoneSimulator.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -2303,6 +2330,7 @@ Global
 		{A0D0A6A4-5C72-4ADA-9B27-621C7D94F270} = {9B9E3891-2366-4253-A952-D08BCEB71098}
 		{70B9F5CC-E2F9-4314-9514-EDE762ACCC4B} = {9B9E3891-2366-4253-A952-D08BCEB71098}
 		{CE910927-CE5A-456F-BC92-E4C757354A5C} = {C5A00AC3-B34C-4564-9BDD-2DA473EF4D8B}
+		{2B390431-288C-435C-BB6B-A374033BD8D1} = {4ED8B739-6F4E-4CD4-B993-545E6B5CE637}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {87366D66-1391-4D90-8999-95A620AD786A}

NuGet.Config

@@ -5,5 +5,6 @@
     <clear />
     <add key="api.nuget.org" value="https://api.nuget.org/v3/index.json" />
     <add key="dotnet-eng" value="https://nuget.avaloniaui.net/repository/avalonia-devdeps/index.json" protocolVersion="3" />
+    <add key="skiasharp" value="https://aka.ms/skiasharp-eap/index.json" />
   </packageSources>
 </configuration>

azure-pipelines.yml

@@ -31,14 +31,14 @@ jobs:
     vmImage: 'ubuntu-20.04'
   steps:
   - task: UseDotNet@2
-    displayName: 'Use .NET Core SDK 3.1.414'
+    displayName: 'Use .NET Core SDK 3.1.418'
     inputs:
-      version: 3.1.414
+      version: 3.1.418
 
   - task: UseDotNet@2
-    displayName: 'Use .NET Core SDK 6.0.100'
+    displayName: 'Use .NET Core SDK 6.0.202'
     inputs:
-      version: 6.0.200
+      version: 6.0.202
 
   - task: CmdLine@2
     displayName: 'Run Build'
@@ -62,14 +62,14 @@ jobs:
     vmImage: 'macOS-10.15'
   steps:
   - task: UseDotNet@2
-    displayName: 'Use .NET Core SDK 3.1.414'
+    displayName: 'Use .NET Core SDK 3.1.418'
     inputs:
-      version: 3.1.414
+      version: 3.1.418
 
   - task: UseDotNet@2
-    displayName: 'Use .NET Core SDK 6.0.100'
+    displayName: 'Use .NET Core SDK 6.0.202'
     inputs:
-      version: 6.0.200
+      version: 6.0.202
       
   - task: CmdLine@2
     displayName: 'Install Mono 5.18'
@@ -134,20 +134,20 @@ jobs:
     SolutionDir: '$(Build.SourcesDirectory)'
   steps:
   - task: UseDotNet@2
-    displayName: 'Use .NET Core SDK 3.1.414'
+    displayName: 'Use .NET Core SDK 3.1.418'
     inputs:
-      version: 3.1.414
+      version: 3.1.418
 
   - task: UseDotNet@2
-    displayName: 'Use .NET Core SDK 6.0.100'
+    displayName: 'Use .NET Core SDK 6.0.202'
     inputs:
-      version: 6.0.200
+      version: 6.0.202
 
   - task: CmdLine@2
     displayName: 'Install Workloads'
     inputs:
       script: |
-       dotnet workload install --no-cache --disable-parallel android ios --skip-manifest-update --source "https://api.nuget.org/v3/index.json"
+       dotnet workload install android ios
 
   - task: CmdLine@2
     displayName: 'Install Nuke'

build/DevAnalyzers.props

@@ -0,0 +1,9 @@
+<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup>
+    <ProjectReference Include="$(MSBuildThisFileDirectory)..\src\Tools\DevAnalyzers\DevAnalyzers.csproj"
+                      PrivateAssets="all"
+                      ReferenceOutputAssembly="false"
+                      OutputItemType="Analyzer"
+                      SetTargetFramework="TargetFramework=netstandard2.0"/>
+  </ItemGroup>
+</Project>

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-preview.209" />
+    <PackageReference Include="HarfBuzzSharp" Version="2.8.2-preview.254" />
-    <PackageReference Condition="'$(IncludeLinuxSkia)' == 'true'" Include="HarfBuzzSharp.NativeAssets.Linux" Version="2.8.2-preview.209" />
+    <PackageReference Condition="'$(IncludeLinuxSkia)' == 'true'" Include="HarfBuzzSharp.NativeAssets.Linux" Version="2.8.2-preview.254" />
-    <PackageReference Condition="'$(IncludeWasmSkia)' == 'true'" Include="HarfBuzzSharp.NativeAssets.WebAssembly" Version="2.8.2-preview.209"/>
+    <PackageReference Condition="'$(IncludeWasmSkia)' == 'true'" Include="HarfBuzzSharp.NativeAssets.WebAssembly" Version="2.8.2-preview.254"/>
   </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="2.88.0-preview.209" />
+    <PackageReference Include="SkiaSharp" Version="2.88.0-preview.254" />
-    <PackageReference Condition="'$(IncludeLinuxSkia)' == 'true'" Include="SkiaSharp.NativeAssets.Linux" Version="2.88.0-preview.209" />
+    <PackageReference Condition="'$(IncludeLinuxSkia)' == 'true'" Include="SkiaSharp.NativeAssets.Linux" Version="2.88.0-preview.254" />
-    <PackageReference Condition="'$(IncludeWasmSkia)' == 'true'" Include="SkiaSharp.NativeAssets.WebAssembly" Version="2.88.0-preview.209"/>
+    <PackageReference Condition="'$(IncludeWasmSkia)' == 'true'" Include="SkiaSharp.NativeAssets.WebAssembly" Version="2.88.0-preview.254"/>
   </ItemGroup>
 </Project>

global.json

@@ -1,11 +1,10 @@
 {
     "sdk": {
-        "version": "6.0.200",
+        "version": "6.0.202",
         "rollForward": "latestFeature"
     },
     "msbuild-sdks": {
         "Microsoft.Build.Traversal": "1.0.43",
-        "Xamarin.Legacy.Sdk": "0.1.2-alpha6",
         "MSBuild.Sdk.Extras": "3.0.22",
         "AggregatePackage.NuGet.Sdk" : "0.1.12"
     }

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

@@ -2461,6 +2461,16 @@ NSArray* AllLoopModes = [NSArray arrayWithObjects: NSDefaultRunLoopMode, NSEvent
     
     if(_parent != nullptr)
     {
+        auto cparent = dynamic_cast<WindowImpl*>(_parent.getRaw());
+        
+        if(cparent != nullptr)
+        {
+            if(cparent->WindowState() == Maximized)
+            {
+                cparent->SetWindowState(Normal);
+            }
+        }
+        
         _parent->GetPosition(&position);
         _parent->BaseEvents->PositionChanged(position);
     }

samples/ControlCatalog.Web/ControlCatalog.Web.csproj

@@ -1,15 +1,14 @@
 <Project Sdk="Microsoft.NET.Sdk.BlazorWebAssembly">
   <PropertyGroup>
     <TargetFramework>net6.0</TargetFramework>
-    <MSBuildEnableWorkloadResolver>false</MSBuildEnableWorkloadResolver>
     <Nullable>enable</Nullable>
-    <WasmBuildNative>True</WasmBuildNative>
+    <!--Temporal hack that fixes compilation in VS-->
+    <TypeScriptCompileBlocked>true</TypeScriptCompileBlocked>
+    <EmccTotalMemory>16777216</EmccTotalMemory>
+    <BlazorEnableTimeZoneSupport>false</BlazorEnableTimeZoneSupport>
+    <BlazorWebAssemblyPreserveCollationData>false</BlazorWebAssemblyPreserveCollationData>
   </PropertyGroup>
 
-  <ItemGroup>
-    <BlazorLinkerDescriptor Include="LinkerConfig.xml" />
-  </ItemGroup>
-
   <!-- In debug, make builds faster by reducing optimizations -->
   <PropertyGroup Condition="'$(Configuration)' == 'Debug'">
     <WasmNativeStrip>false</WasmNativeStrip>
@@ -23,19 +22,36 @@
     <EmccCompileOptimizationFlag>-O3</EmccCompileOptimizationFlag>
     <EmccLinkOptimizationFlag>-O3</EmccLinkOptimizationFlag>
     <RunAOTCompilation>false</RunAOTCompilation>
+    <DebuggerSupport>false</DebuggerSupport>
+    <EnableUnsafeBinaryFormatterSerialization>false</EnableUnsafeBinaryFormatterSerialization>
+    <EnableUnsafeUTF7Encoding>false</EnableUnsafeUTF7Encoding>
+    <EventSourceSupport>false</EventSourceSupport>
+    <HttpActivityPropagationSupport>false</HttpActivityPropagationSupport>
+    <InvariantGlobalization>true</InvariantGlobalization>
+    <MetadataUpdaterSupport>false</MetadataUpdaterSupport>
+    <UseNativeHttpHandler>true</UseNativeHttpHandler>
+    <UseSystemResourceKeys>true</UseSystemResourceKeys>
+    <PublishTrimmed>true</PublishTrimmed>
+    <TrimMode>link</TrimMode>
+    <TrimmerRemoveSymbols>true</TrimmerRemoveSymbols>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly" Version="6.0.0"/>
+    <PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly" Version="6.0.0" />
-    <PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly.DevServer" Version="6.0.0" PrivateAssets="all"/>
+    <PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly.DevServer" Version="6.0.0" PrivateAssets="all" />
   </ItemGroup>
 
-  <Import Project="..\..\src\Web\Avalonia.Web.Blazor\Avalonia.Web.Blazor.targets" />
-  <Import Project="..\..\src\Web\Avalonia.Web.Blazor\Avalonia.Web.Blazor.CompilationTuning.props" />
-
   <ItemGroup>
-    <ProjectReference Include="..\..\src\Web\Avalonia.Web.Blazor\Avalonia.Web.Blazor.csproj"/>
+    <ProjectReference Include="..\..\src\Skia\Avalonia.Skia\Avalonia.Skia.csproj" />
-    <ProjectReference Include="..\ControlCatalog\ControlCatalog.csproj"/>
+    <ProjectReference Include="..\..\src\Web\Avalonia.Web.Blazor\Avalonia.Web.Blazor.csproj" />
+    <ProjectReference Include="..\ControlCatalog\ControlCatalog.csproj" />
   </ItemGroup>
 
+  <Import Project="..\..\build\ReferenceCoreLibraries.props" />
+  <Import Project="..\..\build\BuildTargets.targets" />
+
+  <Import Project="..\..\src\Web\Avalonia.Web.Blazor\Avalonia.Web.Blazor.targets" />
+  <Import Project="..\..\src\Web\Avalonia.Web.Blazor\Avalonia.Web.Blazor.CompilationTuning.props" />
+
 </Project>
+

samples/ControlCatalog.Web/LinkerConfig.xml

@@ -1,28 +0,0 @@
-<?xml version="1.0" encoding="UTF-8" ?>
-<!--
-  This file specifies which parts of the BCL or Blazor packages must not be
-  stripped by the IL Linker even if they aren't referenced by user code.
--->
-<linker>
-  <assembly fullname="mscorlib">
-    <!--
-      Preserve the methods in WasmRuntime because its methods are called by 
-      JavaScript client-side code to implement timers.
-      Fixes: https://github.com/dotnet/blazor/issues/239
-    -->
-    <type fullname="System.Threading.WasmRuntime"/>
-  </assembly>
-
-  <assembly fullname="System.Core">
-    <!--
-      System.Linq.Expressions* is required by Json.NET and any 
-      expression.Compile caller. The assembly isn't stripped.
-    -->
-    <type fullname="System.Linq.Expressions*"/>
-  </assembly>
-  <!--
-    In this example, the app's entry point assembly is listed. The assembly
-    isn't stripped by the IL Linker.
-  -->
-  <assembly fullname="ControlCatalog" preserve="All" />
-</linker>

samples/ControlCatalog/MainView.xaml

@@ -190,6 +190,14 @@
                 <WindowTransparencyLevel>Mica</WindowTransparencyLevel>
               </ComboBox.Items>
             </ComboBox>
+            <ComboBox x:Name="FlowDirection"
+                      HorizontalAlignment="Stretch"
+                      SelectedIndex="0">
+              <ComboBox.Items>
+                <FlowDirection>LeftToRight</FlowDirection>
+                <FlowDirection>RightToLeft</FlowDirection>
+              </ComboBox.Items>
+            </ComboBox>
             <ComboBox HorizontalAlignment="Stretch"
                       Items="{Binding WindowStates}"
                       SelectedItem="{Binding WindowState}" />

samples/ControlCatalog/MainView.xaml.cs

@@ -76,6 +76,15 @@ namespace ControlCatalog
                 }
             };
 
+            var flowDirections = this.Find<ComboBox>("FlowDirection");
+            flowDirections.SelectionChanged += (sender, e) =>
+            {
+                if (flowDirections.SelectedItem is FlowDirection flowDirection)
+                {
+                    this.FlowDirection = flowDirection;
+                }
+            };
+
             var decorations = this.Find<ComboBox>("Decorations");
             decorations.SelectionChanged += (sender, e) =>
             {

samples/ControlCatalog/Pages/ButtonsPage.xaml

@@ -147,6 +147,35 @@
       </StackPanel>
     </Border>
 
+    <!-- DropDownButton -->
+    <Border Classes="header-border">
+      <StackPanel Orientation="Vertical"
+                  Spacing="4">
+        <TextBlock Text="DropDownButton"
+                   Classes="header" />
+        <TextBlock TextWrapping="Wrap">A button with an added drop-down chevron to visually indicate it has a flyout with additional actions.</TextBlock>
+      </StackPanel>
+    </Border>
+
+    <Border Classes="thin"
+            Padding="15">
+      <StackPanel Orientation="Vertical"
+                  Spacing="8">
+        <DropDownButton Flyout="{StaticResource SharedMenuFlyout}">
+          <TextBlock Text="Drop Down Button" />
+        </DropDownButton>
+        <DropDownButton Padding="0,0,8,0">
+          <Border Background="Teal"
+                  HorizontalAlignment="Stretch"
+                  VerticalAlignment="Stretch"
+                  Height="32"
+                  Width="32" />
+        </DropDownButton>
+        <DropDownButton IsEnabled="False">Disabled</DropDownButton>
+        <DropDownButton />
+      </StackPanel>
+    </Border>
+
     <!-- SplitButton -->
     <Border Classes="header-border">
       <StackPanel Orientation="Vertical"
@@ -169,7 +198,8 @@
           <TextBlock Text="Disabled" />
         </SplitButton>
         <SplitButton Flyout="{StaticResource SharedMenuFlyout}"
-                     Content="Re-themed">
+                     Content="Re-themed"
+                     Foreground="White">
           <SplitButton.Styles>
             <Style>
               <Style.Resources>

samples/ControlCatalog/Pages/CanvasPage.xaml

@@ -4,7 +4,7 @@
   <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h2">A panel which lays out its children by explicit coordinates</TextBlock>
     <Canvas Background="Yellow" Width="300" Height="400">
-      <Rectangle Fill="Blue" Width="63" Height="41" Canvas.Left="40" Canvas.Top="31">
+      <Rectangle Fill="Blue" Width="63" Height="41" Canvas.Left="40" Canvas.Top="31" RadiusX="10" RadiusY="10">
         <Rectangle.OpacityMask>
           <LinearGradientBrush StartPoint="0%,0%" EndPoint="100%,100%">
             <LinearGradientBrush.GradientStops>
@@ -12,8 +12,9 @@
               <GradientStop Offset="1" Color="Transparent"/>
             </LinearGradientBrush.GradientStops>
           </LinearGradientBrush>
-        </Rectangle.OpacityMask>     
+        </Rectangle.OpacityMask>
       </Rectangle>
+      <Rectangle Fill="hsva(240, 83%, 73%, 90%)" Stroke="hsl(5, 85%, 85%)" StrokeThickness="2" Width="40" Height="20" Canvas.Left="150" Canvas.Top="10" RadiusX="10" RadiusY="5" />
       <Ellipse Fill="Green" Width="58" Height="58" Canvas.Left="88" Canvas.Top="100"/>
       <Path Fill="Orange" Data="M 0,0 c 0,0 50,0 50,-50 c 0,0 50,0 50,50 h -50 v 50 l -50,-50 Z" Canvas.Left="30" Canvas.Top="250"/>
       <Path Fill="OrangeRed" Canvas.Left="180" Canvas.Top="250">

samples/ControlCatalog/Pages/PointersPage.cs

@@ -8,6 +8,7 @@ using System.Runtime.InteropServices;
 using System.Threading;
 using Avalonia;
 using Avalonia.Controls;
+using Avalonia.Controls.Documents;
 using Avalonia.Input;
 using Avalonia.Layout;
 using Avalonia.Media;
@@ -133,7 +134,7 @@ public class PointersPage : Decorator
     {
         public PointerIntermediatePointsTab()
         {
-            this[TextBlock.ForegroundProperty] = Brushes.Black;
+            this[TextElement.ForegroundProperty] = Brushes.Black;
             var slider = new Slider
             {
                 Margin = new Thickness(5),

samples/ControlCatalog/Pages/ScreenPage.cs

@@ -13,6 +13,8 @@ namespace ControlCatalog.Pages
     {
         private double _leftMost;
 
+        protected override bool BypassFlowDirectionPolicies => true;
+
         protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
         {
             base.OnAttachedToVisualTree(e);

samples/IntegrationTestApp/MainWindow.axaml

@@ -82,12 +82,16 @@
           <Menu DockPanel.Dock="Top">
             <MenuItem Name="RootMenuItem" Header="_Root">
               <MenuItem Name="Child1MenuItem" Header="_Child 1" InputGesture="Ctrl+O" Click="MenuClicked"/>
-              <MenuItem Name="Child2MenuItem" Header="_Child 1">
+              <MenuItem Name="Child2MenuItem" Header="C_hild 2">
                 <MenuItem Name="GrandchildMenuItem" Header="_Grandchild" Click="MenuClicked"/>
               </MenuItem>
             </MenuItem>
           </Menu>
-          <TextBlock Name="ClickedMenuItem">None</TextBlock>
+          <StackPanel>
+            <TextBlock Name="ClickedMenuItem">None</TextBlock>
+            <Button Name="MenuClickedMenuItemReset">Reset</Button>
+            <TextBox Name="MenuFocusTest"/>
+          </StackPanel>
         </DockPanel>
       </TabItem>
     </TabControl>

samples/IntegrationTestApp/MainWindow.axaml.cs

@@ -62,6 +62,8 @@ namespace IntegrationTestApp
                 this.FindControl<ComboBox>("BasicComboBox").SelectedIndex = 0;
             if (source?.Name == "ListBoxSelectionClear")
                 this.FindControl<ListBox>("BasicListBox").SelectedIndex = -1;
+            if (source?.Name == "MenuClickedMenuItemReset")
+                this.FindControl<TextBlock>("ClickedMenuItem").Text = "None";
         }
     }
 }

samples/RenderDemo/MainWindow.xaml

@@ -60,6 +60,9 @@
     <TabItem Header="FormattedText">
       <pages:FormattedTextPage />
     </TabItem>
+    <TabItem Header="TextFormatter">
+      <pages:TextFormatterPage />
+    </TabItem>
     <TabItem Header="LineBounds">
       <pages:LineBoundsPage />
     </TabItem>

samples/RenderDemo/Pages/TextFormatterPage.axaml

@@ -0,0 +1,7 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
+             x:Class="RenderDemo.Pages.TextFormatterPage">
+</UserControl>

samples/RenderDemo/Pages/TextFormatterPage.axaml.cs

@@ -0,0 +1,118 @@
+using System;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+using Avalonia.Media;
+using Avalonia.Media.TextFormatting;
+
+namespace RenderDemo.Pages
+{
+    public class TextFormatterPage : UserControl
+    {
+        private TextLine _textLine;
+        
+        public TextFormatterPage()
+        {
+            this.InitializeComponent();
+        }
+
+        private void InitializeComponent()
+        {
+            AvaloniaXamlLoader.Load(this);
+        }
+        
+        public override void Render(DrawingContext context)
+        {
+            _textLine?.Draw(context, new Point());
+        }
+
+        protected override Size MeasureOverride(Size availableSize)
+        {
+            var defaultRunProperties = new GenericTextRunProperties(Typeface.Default, foregroundBrush: Brushes.Black,
+                baselineAlignment: BaselineAlignment.Center);
+            var paragraphProperties = new GenericTextParagraphProperties(defaultRunProperties);
+
+            var control = new Button { Content = new TextBlock { Text = "ClickMe" } };
+            
+            Content = control;
+            
+            var textSource = new CustomTextSource(control, defaultRunProperties);
+
+            control.Measure(Size.Infinity);
+
+            _textLine =
+                TextFormatter.Current.FormatLine(textSource, 0, double.PositiveInfinity, paragraphProperties);
+            
+            return base.MeasureOverride(availableSize);
+        }
+
+        protected override Size ArrangeOverride(Size finalSize)
+        {
+            var currentX = 0d;
+            
+            foreach (var textRun in _textLine.TextRuns)
+            {
+                if (textRun is ControlRun controlRun)
+                {
+                    controlRun.Control.Arrange(new Rect(new Point(currentX, 0), controlRun.Size));
+                }
+
+                if (textRun is DrawableTextRun drawableTextRun)
+                {
+                    currentX += drawableTextRun.Size.Width;
+                }
+            }
+            
+            return finalSize;
+        }
+
+        private class CustomTextSource : ITextSource
+        {
+            private readonly Control _control;
+            private readonly TextRunProperties _defaultProperties;
+            private readonly string _text = "<-Hello World->";
+
+            public CustomTextSource(Control control, TextRunProperties defaultProperties)
+            {
+                _control = control;
+                _defaultProperties = defaultProperties;
+            }
+            
+            public TextRun? GetTextRun(int textSourceIndex)
+            {
+                if (textSourceIndex >= _text.Length * 2 + TextRun.DefaultTextSourceLength)
+                {
+                    return null;
+                }
+
+                if (textSourceIndex == _text.Length)
+                {
+                    return new ControlRun(_control, _defaultProperties);
+                }
+
+                return new TextCharacters(_text.AsMemory(), _defaultProperties);
+            }
+        }
+
+        private class ControlRun : DrawableTextRun
+        {
+            private readonly Control _control;
+
+            public ControlRun(Control control, TextRunProperties properties)
+            {
+                _control = control;
+                Properties = properties;
+            }
+
+            public Control Control => _control;
+            public override Size Size => _control.DesiredSize;
+            public override double Baseline => 0;
+            public override TextRunProperties? Properties { get; }
+
+            public override void Draw(DrawingContext drawingContext, Point origin)
+            {
+                // noop
+            }
+        }
+    }
+}

samples/RenderDemo/RenderDemo.csproj

@@ -5,6 +5,10 @@
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="..\..\src\Avalonia.Visuals\Rendering\SceneGraph\LineBoundsHelper.cs" Link="LineBoundsHelper.cs" />
+    <Compile Update="Pages\TextFormatterPage.axaml.cs">
+      <DependentUpon>TextFormatterPage.axaml</DependentUpon>
+      <SubType>Code</SubType>
+    </Compile>
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\src\Avalonia.Diagnostics\Avalonia.Diagnostics.csproj" />

samples/SampleControls/HamburgerMenu/HamburgerMenu.xaml

@@ -195,9 +195,9 @@
                               VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
                               Content="{TemplateBinding Header}"
                               ContentTemplate="{TemplateBinding HeaderTemplate}"
-                              TextBlock.FontFamily="{TemplateBinding FontFamily}"
+                              TextElement.FontFamily="{TemplateBinding FontFamily}"
-                              TextBlock.FontSize="{TemplateBinding FontSize}"
+                              TextElement.FontSize="{TemplateBinding FontSize}"
-                              TextBlock.FontWeight="{TemplateBinding FontWeight}" />
+                              TextElement.FontWeight="{TemplateBinding FontWeight}" />
           </Panel>
         </Border>
       </ControlTemplate>
@@ -216,25 +216,25 @@
                           Content="{TemplateBinding Content}"
                           ContentTemplate="{TemplateBinding ContentTemplate}"
                           CornerRadius="{TemplateBinding CornerRadius}"
-                          TextBlock.FontFamily="{TemplateBinding FontFamily}"
+                          TextElement.FontFamily="{TemplateBinding FontFamily}"
-                          TextBlock.FontSize="{TemplateBinding FontSize}"
+                          TextElement.FontSize="{TemplateBinding FontSize}"
-                          TextBlock.FontWeight="{TemplateBinding FontWeight}" />
+                          TextElement.FontWeight="{TemplateBinding FontWeight}" />
       </ControlTemplate>
     </Setter>
   </Style>
   <Style Selector="catalog|HamburgerMenu > TabItem /template/ Border#PART_LayoutRoot, :is(Button).NavigationButton /template/ ContentPresenter">
     <Setter Property="Border.Background" Value="Transparent" />
-    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SystemBaseHighColor}" />
+    <Setter Property="TextElement.Foreground" Value="{DynamicResource SystemBaseHighColor}" />
   </Style>
   <Style Selector="catalog|HamburgerMenu > TabItem:pointerover /template/ Border#PART_LayoutRoot, :is(Button).NavigationButton:pointerover /template/ ContentPresenter">
     <Setter Property="Border.Background" Value="{DynamicResource SystemChromeLowColor}" />
     <Setter Property="Border.BoxShadow" Value="{StaticResource NavigationItemShadow}" />
-    <Setter Property="TextBlock.Foreground" Value="{DynamicResource TabItemHeaderForegroundUnselectedPointerOver}" />
+    <Setter Property="TextElement.Foreground" Value="{DynamicResource TabItemHeaderForegroundUnselectedPointerOver}" />
   </Style>
   <Style Selector="catalog|HamburgerMenu > TabItem:pressed /template/ Border#PART_LayoutRoot, :is(Button).NavigationButton:pressed /template/ ContentPresenter">
     <Setter Property="Border.Background" Value="{DynamicResource SystemChromeLowColor}" />
     <Setter Property="Border.BoxShadow" Value="{StaticResource NavigationItemShadow}" />
-    <Setter Property="TextBlock.Foreground" Value="{DynamicResource TabItemHeaderForegroundUnselectedPressed}" />
+    <Setter Property="TextElement.Foreground" Value="{DynamicResource TabItemHeaderForegroundUnselectedPressed}" />
   </Style>
   <Style Selector=":is(Button).NavigationButton:pressed">
     <Setter Property="RenderTransform" Value="none" />

src/Android/Avalonia.Android/Avalonia.Android.csproj

@@ -1,7 +1,6 @@
-<Project Sdk="Xamarin.Legacy.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>net6.0-android</TargetFrameworks>
+    <TargetFramework>net6.0-android</TargetFramework>
-    <TargetFrameworks Condition="'$(MSBuildRuntimeType)' != 'Core'">$(TargetFrameworks);monoandroid11.0</TargetFrameworks>
     <SupportedOSPlatformVersion>21</SupportedOSPlatformVersion>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <MSBuildEnableWorkloadResolver>true</MSBuildEnableWorkloadResolver>
@@ -16,4 +15,5 @@
     <ProjectReference Include="..\..\Avalonia.Base\Avalonia.Base.csproj" />
     <ProjectReference Include="..\..\Skia\Avalonia.Skia\Avalonia.Skia.csproj" />
   </ItemGroup>
+  <Import Project="..\..\..\build\DevAnalyzers.props" />
 </Project>

src/Avalonia.Animation/Avalonia.Animation.csproj

@@ -11,4 +11,5 @@
   <Import Project="..\..\build\Rx.props" />
   <Import Project="..\..\build\ApiDiff.props" />
   <Import Project="..\..\build\NullableEnable.props" />
+  <Import Project="..\..\build\DevAnalyzers.props" />
 </Project>

src/Avalonia.Animation/Easing/Easing.cs

@@ -39,7 +39,7 @@ namespace Avalonia.Animation.Easings
                 var derivedTypes = typeof(Easing).Assembly.GetTypes()
                                       .Where(p => p.Namespace == s_thisType.Namespace)
                                       .Where(p => p.IsSubclassOf(s_thisType))
-                                      .Select(p => p).ToList();
+                                      .Select(p => p);
 
                 foreach (var easingType in derivedTypes)
                     _easingTypes.Add(easingType.Name, easingType);

src/Avalonia.Base/Avalonia.Base.csproj

@@ -12,4 +12,5 @@
   <Import Project="..\..\build\System.Memory.props" />
   <Import Project="..\..\build\ApiDiff.props" />
   <Import Project="..\..\build\NullableEnable.props" />
+  <Import Project="..\..\build\DevAnalyzers.props" />
 </Project>

src/Avalonia.Base/Collections/AvaloniaDictionary.cs

@@ -123,7 +123,7 @@ namespace Avalonia.Collections
             {
                 var e = new NotifyCollectionChangedEventArgs(
                     NotifyCollectionChangedAction.Remove,
-                    old.ToList(),
+                    old.ToArray(),
                     -1);
                 CollectionChanged(this, e);
             }

src/Avalonia.Base/Collections/AvaloniaList.cs

@@ -222,7 +222,7 @@ namespace Avalonia.Collections
                 {
                     var e = ResetBehavior == ResetBehavior.Reset ?
                         EventArgsCache.ResetCollectionChanged :
-                        new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, _inner.ToList(), 0);
+                        new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, _inner.ToArray(), 0);
 
                     _inner.Clear();
 

src/Avalonia.Base/Data/Core/PropertyPath.cs

@@ -10,7 +10,7 @@ namespace Avalonia.Data.Core
 
         public PropertyPath(IEnumerable<IPropertyPathElement> elements)
         {
-            Elements = elements.ToList();
+            Elements = elements.ToArray();
         }
     }
 

src/Avalonia.Base/Utilities/AvaloniaResourcesIndex.cs

@@ -23,7 +23,7 @@ namespace Avalonia.Utilities
 
             var assetDoc = XDocument.Load(stream);
             XNamespace assetNs = assetDoc.Root!.Attribute("xmlns")!.Value;
-            List<AvaloniaResourcesIndexEntry> entries=         
+            List<AvaloniaResourcesIndexEntry> entries =         
                 (from entry in assetDoc.Root.Element(assetNs + "Entries")!.Elements(assetNs + "AvaloniaResourcesIndexEntry")
                     select new AvaloniaResourcesIndexEntry
                     {

src/Avalonia.Build.Tasks/Avalonia.Build.Tasks.csproj

@@ -83,6 +83,9 @@
       <Compile Include="../Avalonia.Visuals/Media/Color.cs">
         <Link>Markup/%(RecursiveDir)%(FileName)%(Extension)</Link>
       </Compile>
+      <Compile Include="../Avalonia.Visuals/Media/HslColor.cs">
+        <Link>Markup/%(RecursiveDir)%(FileName)%(Extension)</Link>
+      </Compile>
       <Compile Include="../Avalonia.Visuals/Media/HsvColor.cs">
         <Link>Markup/%(RecursiveDir)%(FileName)%(Extension)</Link>
       </Compile>

src/Avalonia.Build.Tasks/GenerateAvaloniaResourcesTask.cs

@@ -105,7 +105,7 @@ namespace Avalonia.Build.Tasks
         {
             var typeToXamlIndex = new Dictionary<string, string>(); 
             
-            foreach (var s in sources.ToList())
+            foreach (var s in sources.ToArray())
             {
                 if (s.Path.ToLowerInvariant().EndsWith(".xaml") || s.Path.ToLowerInvariant().EndsWith(".paml") || s.Path.ToLowerInvariant().EndsWith(".axaml"))
                 {

src/Avalonia.Controls.DataGrid/Avalonia.Controls.DataGrid.csproj

@@ -23,4 +23,5 @@
   <Import Project="..\..\build\JetBrains.Annotations.props" />
   <Import Project="..\..\build\BuildTargets.targets" />
   <Import Project="..\..\build\ApiDiff.props" />
+  <Import Project="..\..\build\DevAnalyzers.props" />
 </Project>

src/Avalonia.Controls.DataGrid/Collections/DataGridCollectionView.cs

@@ -3946,7 +3946,7 @@ namespace Avalonia.Collections
             {
                 sort.Initialize(itemType); 
 
-                if(seq is IOrderedEnumerable<object> orderedEnum)
+                if (seq is IOrderedEnumerable<object> orderedEnum)
                 {
                     seq = sort.ThenBy(orderedEnum);
                 }

src/Avalonia.Controls.DataGrid/DataGrid.cs

@@ -2060,6 +2060,25 @@ namespace Avalonia.Controls
                     forceHorizontalScroll: true);
             }
         }
+        
+        protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
+        {
+            base.OnAttachedToVisualTree(e);
+            if (DataConnection.DataSource != null && !DataConnection.EventsWired)
+            {
+                DataConnection.WireEvents(DataConnection.DataSource);
+            }
+        }
+
+        protected override void OnDetachedFromVisualTree(VisualTreeAttachmentEventArgs e)
+        {
+            base.OnDetachedFromVisualTree(e);
+            // When wired to INotifyCollectionChanged, the DataGrid will be cleaned up by GC
+            if (DataConnection.DataSource != null && DataConnection.EventsWired)
+            {
+                DataConnection.UnWireEvents(DataConnection.DataSource);
+            }
+        }
 
         /// <summary>
         /// Arranges the content of the <see cref="T:Avalonia.Controls.DataGridRow" />.

src/Avalonia.Controls.DataGrid/DataGridTextColumn.cs

@@ -10,6 +10,7 @@ using System;
 using System.ComponentModel;
 using Avalonia.Layout;
 using Avalonia.Markup.Xaml.MarkupExtensions;
+using Avalonia.Controls.Documents;
 
 namespace Avalonia.Controls
 {
@@ -32,7 +33,7 @@ namespace Avalonia.Controls
         /// Identifies the FontFamily dependency property.
         /// </summary>
         public static readonly AttachedProperty<FontFamily> FontFamilyProperty =
-            TextBlock.FontFamilyProperty.AddOwner<DataGridTextColumn>();
+            TextElement.FontFamilyProperty.AddOwner<DataGridTextColumn>();
 
         /// <summary>
         /// Gets or sets the font name.
@@ -47,7 +48,7 @@ namespace Avalonia.Controls
         /// Identifies the FontSize dependency property.
         /// </summary>
         public static readonly AttachedProperty<double> FontSizeProperty =
-            TextBlock.FontSizeProperty.AddOwner<DataGridTextColumn>();
+            TextElement.FontSizeProperty.AddOwner<DataGridTextColumn>();
 
         /// <summary>
         /// Gets or sets the font size.
@@ -64,7 +65,7 @@ namespace Avalonia.Controls
         /// Identifies the FontStyle dependency property.
         /// </summary>
         public static readonly AttachedProperty<FontStyle> FontStyleProperty =
-            TextBlock.FontStyleProperty.AddOwner<DataGridTextColumn>();
+            TextElement.FontStyleProperty.AddOwner<DataGridTextColumn>();
 
         /// <summary>
         /// Gets or sets the font style.
@@ -79,7 +80,7 @@ namespace Avalonia.Controls
         /// Identifies the FontWeight dependency property.
         /// </summary>
         public static readonly AttachedProperty<FontWeight> FontWeightProperty =
-            TextBlock.FontWeightProperty.AddOwner<DataGridTextColumn>();
+            TextElement.FontWeightProperty.AddOwner<DataGridTextColumn>();
 
         /// <summary>
         /// Gets or sets the font weight or thickness.
@@ -90,11 +91,26 @@ namespace Avalonia.Controls
             set => SetValue(FontWeightProperty, value);
         }
 
+        /// <summary>
+        /// Identifies the FontStretch dependency property.
+        /// </summary>
+        public static readonly AttachedProperty<FontStretch> FontStretchProperty =
+            TextElement.FontStretchProperty.AddOwner<DataGridTextColumn>();
+
+        /// <summary>
+        /// Gets or sets the font weight or thickness.
+        /// </summary>
+        public FontStretch FontStretch
+        {
+            get => GetValue(FontStretchProperty);
+            set => SetValue(FontStretchProperty, value);
+        }
+
         /// <summary>
         /// Identifies the Foreground dependency property.
         /// </summary>
         public static readonly AttachedProperty<IBrush> ForegroundProperty =
-            TextBlock.ForegroundProperty.AddOwner<DataGridTextColumn>();
+            TextElement.ForegroundProperty.AddOwner<DataGridTextColumn>();
 
         /// <summary>
         /// Gets or sets a brush that describes the foreground of the column cells.

src/Avalonia.Controls.DataGrid/Themes/Default.xaml

@@ -17,7 +17,7 @@
           <ContentPresenter ContentTemplate="{TemplateBinding ContentTemplate}"
                             Content="{TemplateBinding Content}"
                             Margin="{TemplateBinding Padding}"
-                            TextBlock.Foreground="{TemplateBinding Foreground}"
+                            TextElement.Foreground="{TemplateBinding Foreground}"
                             HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                             VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
 

src/Avalonia.Controls.DataGrid/Themes/Fluent.xaml

@@ -124,7 +124,7 @@
           <ContentPresenter ContentTemplate="{TemplateBinding ContentTemplate}"
                             Content="{TemplateBinding Content}"
                             Margin="{TemplateBinding Padding}"
-                            TextBlock.Foreground="{TemplateBinding Foreground}"
+                            TextElement.Foreground="{TemplateBinding Foreground}"
                             HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                             VerticalAlignment="{TemplateBinding VerticalContentAlignment}" />
 

src/Avalonia.Controls/ApiCompatBaseline.txt

@@ -1,4 +1,6 @@
 Compat issues with assembly Avalonia.Controls:
+TypesMustExist : Type 'Avalonia.Controls.DropDown' does not exist in the implementation but it does exist in the contract.
+TypesMustExist : Type 'Avalonia.Controls.DropDownItem' does not exist in the implementation but it does exist in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public System.Boolean Avalonia.Controls.IMenuItem.StaysOpenOnClick' is present in the implementation but not in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public System.Boolean Avalonia.Controls.IMenuItem.StaysOpenOnClick.get()' is present in the implementation but not in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Controls.IMenuItem.StaysOpenOnClick.set(System.Boolean)' is present in the implementation but not in the contract.
@@ -29,6 +31,26 @@ MembersMustExist : Member 'public void Avalonia.Controls.NumericUpDownValueChang
 MembersMustExist : Member 'public System.Double Avalonia.Controls.NumericUpDownValueChangedEventArgs.NewValue.get()' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'public System.Double Avalonia.Controls.NumericUpDownValueChangedEventArgs.OldValue.get()' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'public Avalonia.StyledProperty<System.Boolean> Avalonia.StyledProperty<System.Boolean> Avalonia.Controls.ScrollViewer.AllowAutoHideProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.AttachedProperty<Avalonia.Media.FontFamily> Avalonia.AttachedProperty<Avalonia.Media.FontFamily> Avalonia.Controls.TextBlock.FontFamilyProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.AttachedProperty<Avalonia.Media.FontStyle> Avalonia.AttachedProperty<Avalonia.Media.FontStyle> Avalonia.Controls.TextBlock.FontStyleProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.AttachedProperty<Avalonia.Media.FontWeight> Avalonia.AttachedProperty<Avalonia.Media.FontWeight> Avalonia.Controls.TextBlock.FontWeightProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.AttachedProperty<Avalonia.Media.IBrush> Avalonia.AttachedProperty<Avalonia.Media.IBrush> Avalonia.Controls.TextBlock.ForegroundProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.AttachedProperty<System.Double> Avalonia.AttachedProperty<System.Double> Avalonia.Controls.TextBlock.FontSizeProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.StyledProperty<Avalonia.Media.TextAlignment> Avalonia.StyledProperty<Avalonia.Media.TextAlignment> Avalonia.Controls.TextBlock.TextAlignmentProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.StyledProperty<Avalonia.Media.TextTrimming> Avalonia.StyledProperty<Avalonia.Media.TextTrimming> Avalonia.Controls.TextBlock.TextTrimmingProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.StyledProperty<Avalonia.Media.TextWrapping> Avalonia.StyledProperty<Avalonia.Media.TextWrapping> Avalonia.Controls.TextBlock.TextWrappingProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.StyledProperty<System.Double> Avalonia.StyledProperty<System.Double> Avalonia.Controls.TextBlock.LineHeightProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.StyledProperty<System.Int32> Avalonia.StyledProperty<System.Int32> Avalonia.Controls.TextBlock.MaxLinesProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.Media.FontFamily Avalonia.Controls.TextBlock.GetFontFamily(Avalonia.Controls.Control)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Double Avalonia.Controls.TextBlock.GetFontSize(Avalonia.Controls.Control)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.Media.FontStyle Avalonia.Controls.TextBlock.GetFontStyle(Avalonia.Controls.Control)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.Media.FontWeight Avalonia.Controls.TextBlock.GetFontWeight(Avalonia.Controls.Control)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.Media.IBrush Avalonia.Controls.TextBlock.GetForeground(Avalonia.Controls.Control)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public void Avalonia.Controls.TextBlock.SetFontFamily(Avalonia.Controls.Control, Avalonia.Media.FontFamily)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public void Avalonia.Controls.TextBlock.SetFontSize(Avalonia.Controls.Control, System.Double)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public void Avalonia.Controls.TextBlock.SetFontStyle(Avalonia.Controls.Control, Avalonia.Media.FontStyle)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public void Avalonia.Controls.TextBlock.SetFontWeight(Avalonia.Controls.Control, Avalonia.Media.FontWeight)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public void Avalonia.Controls.TextBlock.SetForeground(Avalonia.Controls.Control, Avalonia.Media.IBrush)' does not exist in the implementation but it does exist in the contract.
 CannotRemoveBaseTypeOrInterface : Type 'Avalonia.Controls.TopLevel' does not implement interface 'Avalonia.Utilities.IWeakSubscriber<Avalonia.Controls.ResourcesChangedEventArgs>' in the implementation but it does in the contract.
 CannotRemoveBaseTypeOrInterface : Type 'Avalonia.Controls.Viewbox' does not inherit from base type 'Avalonia.Controls.Decorator' in the implementation but it does in the contract.
 MembersMustExist : Member 'public Avalonia.AvaloniaProperty<Avalonia.Media.Stretch> Avalonia.AvaloniaProperty<Avalonia.Media.Stretch> Avalonia.Controls.Viewbox.StretchProperty' does not exist in the implementation but it does exist in the contract.
@@ -72,4 +94,4 @@ InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Platfor
 MembersMustExist : Member 'public void Avalonia.Platform.IWindowImpl.Resize(Avalonia.Size)' does not exist in the implementation but it does exist in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Platform.IWindowImpl.Resize(Avalonia.Size, Avalonia.Platform.PlatformResizeReason)' is present in the implementation but not in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public Avalonia.Platform.ITrayIconImpl Avalonia.Platform.IWindowingPlatform.CreateTrayIcon()' is present in the implementation but not in the contract.
-Total Issues: 73
+Total Issues: 95

src/Avalonia.Controls/ApplicationLifetimes/ClassicDesktopStyleApplicationLifetime.cs

@@ -65,7 +65,7 @@ namespace Avalonia.Controls.ApplicationLifetimes
         /// <inheritdoc/>
         public Window? MainWindow { get; set; }
 
-        public IReadOnlyList<Window> Windows => _windows.ToList();
+        public IReadOnlyList<Window> Windows => _windows.ToArray();
 
         private void HandleWindowClosed(Window window)
         {

src/Avalonia.Controls/AutoCompleteBox.cs

@@ -252,6 +252,10 @@ namespace Avalonia.Controls
     /// drop-down that contains possible matches based on the input in the text
     /// box.
     /// </summary>
+    [TemplatePart(ElementPopup,            typeof(Popup))]
+    [TemplatePart(ElementSelector,         typeof(SelectingItemsControl))]
+    [TemplatePart(ElementSelectionAdapter, typeof(ISelectionAdapter))]
+    [TemplatePart(ElementTextBox,          typeof(TextBox))]
     [PseudoClasses(":dropdownopen")]
     public class AutoCompleteBox : TemplatedControl
     {
@@ -2180,7 +2184,7 @@ namespace Avalonia.Controls
             }
 
             // Store a local cached copy of the data
-            _items = newValue == null ? null : new List<object>(newValue.Cast<object>().ToList());
+            _items = newValue == null ? null : new List<object>(newValue.Cast<object>());
 
             // Clear and set the view on the selection adapter
             ClearView();
@@ -2239,7 +2243,7 @@ namespace Avalonia.Controls
                 ClearView();
                 if (Items != null)
                 {
-                    _items = new List<object>(Items.Cast<object>().ToList());
+                    _items = new List<object>(Items.Cast<object>());
                 }
             }
 

src/Avalonia.Controls/Avalonia.Controls.csproj

@@ -19,4 +19,5 @@
   <Import Project="..\..\build\JetBrains.Annotations.props" />
   <Import Project="..\..\build\ApiDiff.props" />
   <Import Project="..\..\build\NullableEnable.props" />
+  <Import Project="..\..\build\DevAnalyzers.props" />
 </Project>

src/Avalonia.Controls/Button.cs

@@ -29,11 +29,14 @@ namespace Avalonia.Controls
     }
 
     /// <summary>
-    /// A button control.
+    /// A standard button control.
     /// </summary>
-    [PseudoClasses(":pressed")]
+    [PseudoClasses(pcFlyoutOpen, pcPressed)]
-    public class Button : ContentControl, ICommandSource
+    public class Button : ContentControl, ICommandSource, IClickableControl
     {
+        protected const string pcPressed    = ":pressed";
+        protected const string pcFlyoutOpen = ":flyout-open";
+
         /// <summary>
         /// Defines the <see cref="ClickMode"/> property.
         /// </summary>
@@ -92,6 +95,7 @@ namespace Avalonia.Controls
         private ICommand? _command;
         private bool _commandCanExecute = true;
         private KeyGesture? _hotkey;
+        private bool _isFlyoutOpen = false;
 
         /// <summary>
         /// Initializes static members of the <see cref="Button"/> class.
@@ -107,7 +111,6 @@ namespace Avalonia.Controls
         /// </summary>
         public Button()
         {
-            UpdatePseudoClasses(IsPressed);
         }
 
         /// <summary>
@@ -328,11 +331,30 @@ namespace Avalonia.Controls
             }
         }
 
+        /// <summary>
+        /// Opens the button's flyout.
+        /// </summary>
         protected virtual void OpenFlyout()
         {
             Flyout?.ShowAt(this);
         }
 
+        /// <summary>
+        /// Invoked when the button's flyout is opened.
+        /// </summary>
+        protected virtual void OnFlyoutOpened()
+        {
+            // Available for derived types
+        }
+
+        /// <summary>
+        /// Invoked when the button's flyout is closed.
+        /// </summary>
+        protected virtual void OnFlyoutClosed()
+        {
+            // Available for derived types
+        }
+
         /// <inheritdoc/>
         protected override void OnPointerPressed(PointerPressedEventArgs e)
         {
@@ -382,6 +404,14 @@ namespace Avalonia.Controls
             IsPressed = false;
         }
 
+        /// <inheritdoc/>
+        protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
+        {
+            UnregisterFlyoutEvents(Flyout);
+            RegisterFlyoutEvents(Flyout);
+            UpdatePseudoClasses();
+        }
+
         /// <inheritdoc/>
         protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> change)
         {
@@ -442,17 +472,26 @@ namespace Avalonia.Controls
             }
             else if (change.Property == IsPressedProperty)
             {
-                UpdatePseudoClasses(change.NewValue.GetValueOrDefault<bool>());
+                UpdatePseudoClasses();
             }
             else if (change.Property == FlyoutProperty)
             {
+                var oldFlyout = change.OldValue.GetValueOrDefault() as FlyoutBase;
+                var newFlyout = change.NewValue.GetValueOrDefault() as FlyoutBase;
+
                 // If flyout is changed while one is already open, make sure we 
                 // close the old one first
-                if (change.OldValue.GetValueOrDefault() is FlyoutBase oldFlyout &&
+                if (oldFlyout != null &&
                     oldFlyout.IsOpen)
                 {
                     oldFlyout.Hide();
                 }
+
+                // Must unregister events here while a reference to the old flyout still exists
+                UnregisterFlyoutEvents(oldFlyout);
+
+                RegisterFlyoutEvents(newFlyout);
+                UpdatePseudoClasses();
             }
         }
 
@@ -493,6 +532,32 @@ namespace Avalonia.Controls
             }
         }
 
+        /// <summary>
+        /// Registers all flyout events.
+        /// </summary>
+        /// <param name="flyout">The flyout to connect events to.</param>
+        private void RegisterFlyoutEvents(FlyoutBase? flyout)
+        {
+            if (flyout != null)
+            {
+                flyout.Opened += Flyout_Opened;
+                flyout.Closed += Flyout_Closed;
+            }
+        }
+
+        /// <summary>
+        /// Explicitly unregisters all flyout events.
+        /// </summary>
+        /// <param name="flyout">The flyout to disconnect events from.</param>
+        private void UnregisterFlyoutEvents(FlyoutBase? flyout)
+        {
+            if (flyout != null)
+            {
+                flyout.Opened -= Flyout_Opened;
+                flyout.Closed -= Flyout_Closed;
+             }
+        }
+
         /// <summary>
         /// Starts listening for the Enter key when the button <see cref="IsDefault"/>.
         /// </summary>
@@ -560,11 +625,53 @@ namespace Avalonia.Controls
         /// <summary>
         /// Updates the visual state of the control by applying latest PseudoClasses.
         /// </summary>
-        private void UpdatePseudoClasses(bool isPressed)
+        private void UpdatePseudoClasses()
         {
-            PseudoClasses.Set(":pressed", isPressed);
+            PseudoClasses.Set(pcFlyoutOpen, _isFlyoutOpen);
+            PseudoClasses.Set(pcPressed, IsPressed);
         }
 
         void ICommandSource.CanExecuteChanged(object sender, EventArgs e) => this.CanExecuteChanged(sender, e);
+
+        void IClickableControl.RaiseClick() => OnClick();
+        
+        /// <summary>
+        /// Event handler for when the button's flyout is opened.
+        /// </summary>
+        private void Flyout_Opened(object? sender, EventArgs e)
+        {
+            var flyout = sender as FlyoutBase;
+
+            // It is possible to share flyouts among multiple controls including Button.
+            // This can cause a problem here since all controls that share a flyout receive
+            // the same Opened/Closed events at the same time.
+            // For Button that means they all would be updating their pseudoclasses accordingly.
+            // In other words, all Buttons with a shared Flyout would have the backgrounds changed together.
+            // To fix this, only continue here if the Flyout target matches this Button instance.
+            if (object.ReferenceEquals(flyout?.Target, this))
+            {
+                _isFlyoutOpen = true;
+                UpdatePseudoClasses();
+
+                OnFlyoutOpened();
+            }
+        }
+
+        /// <summary>
+        /// Event handler for when the button's flyout is closed.
+        /// </summary>
+        private void Flyout_Closed(object? sender, EventArgs e)
+        {
+            var flyout = sender as FlyoutBase;
+
+            // See comments in Flyout_Opened
+            if (object.ReferenceEquals(flyout?.Target, this))
+            {
+                _isFlyoutOpen = false;
+                UpdatePseudoClasses();
+
+                OnFlyoutClosed();
+            }
+        }
     }
 }

src/Avalonia.Controls/ButtonSpinner.cs

@@ -16,6 +16,8 @@ namespace Avalonia.Controls
     /// <summary>
     /// Represents a spinner control that includes two Buttons.
     /// </summary>
+    [TemplatePart("PART_DecreaseButton", typeof(Button))]
+    [TemplatePart("PART_IncreaseButton", typeof(Button))]
     [PseudoClasses(":left", ":right")]
     public class ButtonSpinner : Spinner
     {

src/Avalonia.Controls/Calendar/Calendar.cs

@@ -6,6 +6,7 @@
 using System;
 using System.Collections.ObjectModel;
 using System.Diagnostics;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Data;
 using Avalonia.Input;
@@ -222,6 +223,8 @@ namespace Avalonia.Controls
     /// element in XAML.
     /// </para>
     /// </remarks>
+    [TemplatePart(PART_ElementMonth, typeof(CalendarItem))]
+    [TemplatePart(PART_ElementRoot,  typeof(Panel))]
     public class Calendar : TemplatedControl
     {
         internal const int RowsPerMonth = 7;
@@ -261,6 +264,7 @@ namespace Avalonia.Controls
             AvaloniaProperty.Register<Calendar, DayOfWeek>(
                     nameof(FirstDayOfWeek),
                     defaultValue: DateTimeHelper.GetCurrentDateFormat().FirstDayOfWeek);
+
         /// <summary>
         /// Gets or sets the day that is considered the beginning of the week.
         /// </summary>
@@ -273,6 +277,7 @@ namespace Avalonia.Controls
             get { return GetValue(FirstDayOfWeekProperty); }
             set { SetValue(FirstDayOfWeekProperty, value); }
         }
+
         /// <summary>
         /// FirstDayOfWeekProperty property changed handler.
         /// </summary>
@@ -289,6 +294,7 @@ namespace Avalonia.Controls
                 throw new ArgumentOutOfRangeException("d", "Invalid DayOfWeek");
             }
         }
+
         /// <summary>
         /// Inherited code: Requires comment.
         /// </summary>
@@ -311,6 +317,7 @@ namespace Avalonia.Controls
             AvaloniaProperty.Register<Calendar, bool>(
                 nameof(IsTodayHighlighted),
                 defaultValue: true);
+
         /// <summary>
         /// Gets or sets a value indicating whether the current date is
         /// highlighted.
@@ -324,6 +331,7 @@ namespace Avalonia.Controls
             get { return GetValue(IsTodayHighlightedProperty); }
             set { SetValue(IsTodayHighlightedProperty, value); }
         }
+
         /// <summary>
         /// IsTodayHighlightedProperty property changed handler.
         /// </summary>
@@ -343,6 +351,7 @@ namespace Avalonia.Controls
 
         public static readonly StyledProperty<IBrush> HeaderBackgroundProperty =
             AvaloniaProperty.Register<Calendar, IBrush>(nameof(HeaderBackground));
+
         public IBrush HeaderBackground
         {
             get { return GetValue(HeaderBackgroundProperty); }
@@ -367,6 +376,7 @@ namespace Avalonia.Controls
             get { return GetValue(DisplayModeProperty); }
             set { SetValue(DisplayModeProperty, value); }
         }
+
         /// <summary>
         /// DisplayModeProperty property changed handler.
         /// </summary>
@@ -424,6 +434,7 @@ namespace Avalonia.Controls
                 || mode == CalendarMode.Year
                 || mode == CalendarMode.Decade;
         }
+
         private void OnDisplayModeChanged(CalendarModeChangedEventArgs args)
         {
             DisplayModeChanged?.Invoke(this, args);
@@ -433,6 +444,7 @@ namespace Avalonia.Controls
             AvaloniaProperty.Register<Calendar, CalendarSelectionMode>(
                 nameof(SelectionMode),
                 defaultValue: CalendarSelectionMode.SingleDate);
+
         /// <summary>
         /// Gets or sets a value that indicates what kind of selections are
         /// allowed.
@@ -457,6 +469,7 @@ namespace Avalonia.Controls
             get { return GetValue(SelectionModeProperty); }
             set { SetValue(SelectionModeProperty, value); }
         }
+
         private void OnSelectionModeChanged(AvaloniaPropertyChangedEventArgs e)
         {
             if (IsValidSelectionMode(e.NewValue!))
@@ -471,6 +484,7 @@ namespace Avalonia.Controls
                 throw new ArgumentOutOfRangeException("d", "Invalid SelectionMode");
             }
         }
+
         /// <summary>
         /// Inherited code: Requires comment.
         /// </summary>
@@ -492,6 +506,7 @@ namespace Avalonia.Controls
                 o => o.SelectedDate,
                 (o, v) => o.SelectedDate = v,
                 defaultBindingMode: BindingMode.TwoWay);
+
         /// <summary>
         /// Gets or sets the currently selected date.
         /// </summary>
@@ -720,6 +735,7 @@ namespace Avalonia.Controls
                 o => o.DisplayDate,
                 (o, v) => o.DisplayDate = v,
                 defaultBindingMode: BindingMode.TwoWay);
+
         /// <summary>
         /// Gets or sets the date to display.
         /// </summary>
@@ -1973,6 +1989,7 @@ namespace Avalonia.Controls
                     }
             }
         }
+
         private void Calendar_KeyUp(KeyEventArgs e)
         {
             if (!e.Handled && (e.Key == Key.LeftShift || e.Key == Key.RightShift))
@@ -1980,6 +1997,7 @@ namespace Avalonia.Controls
                 ProcessShiftKeyUp();
             }
         }
+
         internal void ProcessShiftKeyUp()
         {
             if (_isShiftPressed && (SelectionMode == CalendarSelectionMode.SingleRange || SelectionMode == CalendarSelectionMode.MultipleRange))
@@ -2028,6 +2046,7 @@ namespace Avalonia.Controls
                     }
             }
         }
+
         protected override void OnLostFocus(RoutedEventArgs e)
         {
             base.OnLostFocus(e);
@@ -2054,6 +2073,7 @@ namespace Avalonia.Controls
                     }
             }
         }
+
         /// <summary>
         ///  Called when the IsEnabled property changes.
         /// </summary>
@@ -2098,6 +2118,7 @@ namespace Avalonia.Controls
 
         private const string PART_ElementRoot = "Root";
         private const string PART_ElementMonth = "CalendarItem";
+
         /// <summary>
         /// Builds the visual tree for the
         /// <see cref="T:System.Windows.Controls.Calendar" /> when a new

src/Avalonia.Controls/Calendar/CalendarDatePicker.cs

@@ -7,6 +7,7 @@ using System;
 using System.Collections.ObjectModel;
 using System.Diagnostics;
 using System.Globalization;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Data;
 using Avalonia.Input;
@@ -116,6 +117,10 @@ namespace Avalonia.Controls
         Custom = 2
     }
 
+    [TemplatePart(ElementButton,   typeof(Button))]
+    [TemplatePart(ElementCalendar, typeof(Calendar))]
+    [TemplatePart(ElementPopup,    typeof(Popup))]
+    [TemplatePart(ElementTextBox,  typeof(TextBox))]
     public class CalendarDatePicker : TemplatedControl
     {
         private const string ElementTextBox = "PART_TextBox";

src/Avalonia.Controls/Calendar/CalendarItem.cs

@@ -19,6 +19,11 @@ namespace Avalonia.Controls.Primitives
     /// Represents the currently displayed month or year on a
     /// <see cref="T:Avalonia.Controls.Calendar" />.
     /// </summary>
+    [TemplatePart(PART_ElementHeaderButton,   typeof(Button))]
+    [TemplatePart(PART_ElementMonthView,      typeof(Grid))]
+    [TemplatePart(PART_ElementNextButton,     typeof(Button))]
+    [TemplatePart(PART_ElementPreviousButton, typeof(Button))]
+    [TemplatePart(PART_ElementYearView,       typeof(Grid))]
     [PseudoClasses(":calendardisabled")]
     public sealed class CalendarItem : TemplatedControl
     {

src/Avalonia.Controls/Chrome/CaptionButtons.cs

@@ -8,6 +8,10 @@ namespace Avalonia.Controls.Chrome
     /// <summary>
     /// Draws window minimize / maximize / close buttons in a <see cref="TitleBar"/> when managed client decorations are enabled.
     /// </summary>
+    [TemplatePart("PART_CloseButton",      typeof(Panel))]
+    [TemplatePart("PART_RestoreButton",    typeof(Panel))]
+    [TemplatePart("PART_MinimiseButton",   typeof(Panel))]
+    [TemplatePart("PART_FullScreenButton", typeof(Panel))]
     [PseudoClasses(":minimized", ":normal", ":maximized", ":fullscreen")]
     public class CaptionButtons : TemplatedControl
     {

src/Avalonia.Controls/Chrome/TitleBar.cs

@@ -8,6 +8,7 @@ namespace Avalonia.Controls.Chrome
     /// <summary>
     /// Draws a titlebar when managed client decorations are enabled.
     /// </summary>
+    [TemplatePart("PART_CaptionButtons", typeof(CaptionButtons))]
     [PseudoClasses(":minimized", ":normal", ":maximized", ":fullscreen")]
     public class TitleBar : TemplatedControl
     {

src/Avalonia.Controls/ComboBox.cs

@@ -13,12 +13,14 @@ using Avalonia.Interactivity;
 using Avalonia.Layout;
 using Avalonia.Media;
 using Avalonia.VisualTree;
+using Avalonia.Controls.Metadata;
 
 namespace Avalonia.Controls
 {
     /// <summary>
     /// A drop-down list control.
     /// </summary>
+    [TemplatePart("PART_Popup", typeof(Popup))]
     public class ComboBox : SelectingItemsControl
     {
         /// <summary>
@@ -182,6 +184,25 @@ namespace Avalonia.Controls
             this.UpdateSelectionBoxItem(SelectedItem);
         }
 
+        // Because the SelectedItem isn't connected to the visual tree
+        public override void InvalidateMirrorTransform()
+        {
+            base.InvalidateMirrorTransform();
+
+            if (SelectedItem is Control selectedControl)
+            {
+                selectedControl.InvalidateMirrorTransform();
+
+                foreach (var visual in selectedControl.GetVisualDescendants())
+                {
+                    if (visual is Control childControl)
+                    {
+                        childControl.InvalidateMirrorTransform();
+                    }
+                }
+            }
+        }
+
         /// <inheritdoc/>
         protected override void OnKeyDown(KeyEventArgs e)
         {

src/Avalonia.Controls/ContentControl.cs

@@ -1,4 +1,5 @@
 using Avalonia.Collections;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Mixins;
 using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Primitives;
@@ -12,6 +13,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// Displays <see cref="Content"/> according to a <see cref="FuncDataTemplate"/>.
     /// </summary>
+    [TemplatePart("PART_ContentPresenter", typeof(IContentPresenter))]
     public class ContentControl : TemplatedControl, IContentControl, IContentPresenterHost
     {
         /// <summary>

src/Avalonia.Controls/Control.cs

@@ -1,7 +1,7 @@
 using System;
 using System.ComponentModel;
-using System.Runtime.CompilerServices;
 using Avalonia.Automation.Peers;
+using Avalonia.Controls.Documents;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
 using Avalonia.Input;
@@ -67,7 +67,7 @@ namespace Avalonia.Controls
         /// </summary>
         public static readonly AttachedProperty<FlowDirection> FlowDirectionProperty =
             AvaloniaProperty.RegisterAttached<Control, Control, FlowDirection>(nameof(FlowDirection), inherits: true);
-        
+
         private DataTemplates? _dataTemplates;
         private IControl? _focusAdorner;
         private AutomationPeer? _automationPeer;
@@ -137,9 +137,39 @@ namespace Avalonia.Controls
 
         public new IControl? Parent => (IControl?)base.Parent;
 
+        /// <summary>
+        /// Gets the value of the attached <see cref="FlowDirectionProperty"/> on a control.
+        /// </summary>
+        /// <param name="control">The control.</param>
+        /// <returns>The flow direction.</returns>
+        public static FlowDirection GetFlowDirection(Control control)
+        {
+            return control.GetValue(FlowDirectionProperty);
+        }
+
+        /// <summary>
+        /// Sets the value of the attached <see cref="FlowDirectionProperty"/> on a control.
+        /// </summary>
+        /// <param name="control">The control.</param>
+        /// <param name="value">The property value to set.</param>
+        public static void SetFlowDirection(Control control, FlowDirection value)
+        {
+            control.SetValue(FlowDirectionProperty, value);
+        }
+
         /// <inheritdoc/>
         bool IDataTemplateHost.IsDataTemplatesInitialized => _dataTemplates != null;
 
+        /// <summary>
+        /// Gets a value indicating whether control bypass FlowDirecton policies.
+        /// </summary>
+        /// <remarks>
+        /// Related to FlowDirection system and returns false as default, so if 
+        /// <see cref="FlowDirection"/> is RTL then control will get a mirror presentation. 
+        /// For controls that want to avoid this behavior, override this property and return true.
+        /// </remarks>
+        protected virtual bool BypassFlowDirectionPolicies => false;
+
         /// <inheritdoc/>
         void ISetterValue.Initialize(ISetter setter)
         {
@@ -199,6 +229,14 @@ namespace Avalonia.Controls
             base.OnDetachedFromVisualTreeCore(e);
         }
 
+        /// <inheritdoc/>
+        protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
+        {
+            base.OnAttachedToVisualTree(e);
+
+            InvalidateMirrorTransform();
+        }
+
         /// <inheritdoc/>
         protected override void OnGotFocus(GotFocusEventArgs e)
         {
@@ -309,5 +347,55 @@ namespace Avalonia.Controls
                 }
             }
         }
+
+        protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> change)
+        {
+            base.OnPropertyChanged(change);
+
+            if (change.Property == FlowDirectionProperty)
+            {
+                InvalidateMirrorTransform();
+                
+                foreach (var visual in VisualChildren)
+                {
+                    if (visual is Control child)
+                    {
+                        child.InvalidateMirrorTransform();
+                    }
+                }
+            }
+        }
+
+        /// <summary>
+        /// Computes the <see cref="IVisual.HasMirrorTransform"/> value according to the 
+        /// <see cref="FlowDirection"/> and <see cref="BypassFlowDirectionPolicies"/>
+        /// </summary>
+        public virtual void InvalidateMirrorTransform()
+        {
+            var flowDirection = this.FlowDirection;
+            var parentFlowDirection = FlowDirection.LeftToRight;
+
+            bool bypassFlowDirectionPolicies = BypassFlowDirectionPolicies;
+            bool parentBypassFlowDirectionPolicies = false;
+
+            var parent = this.FindAncestorOfType<Control>();
+            if (parent != null)
+            {
+                parentFlowDirection = parent.FlowDirection;
+                parentBypassFlowDirectionPolicies = parent.BypassFlowDirectionPolicies;
+            }
+            else if (Parent is Control logicalParent)
+            {
+                parentFlowDirection = logicalParent.FlowDirection;
+                parentBypassFlowDirectionPolicies = logicalParent.BypassFlowDirectionPolicies;
+            }
+
+            bool thisShouldBeMirrored = flowDirection == FlowDirection.RightToLeft && !bypassFlowDirectionPolicies;
+            bool parentShouldBeMirrored = parentFlowDirection == FlowDirection.RightToLeft && !parentBypassFlowDirectionPolicies;
+
+            bool shouldApplyMirrorTransform = thisShouldBeMirrored != parentShouldBeMirrored;
+
+            HasMirrorTransform = shouldApplyMirrorTransform;
+        }
     }
 }

src/Avalonia.Controls/DateTimePickers/DatePicker.cs

@@ -14,6 +14,15 @@ namespace Avalonia.Controls
     /// <summary>
     /// A control to allow the user to select a date
     /// </summary>
+    [TemplatePart("ButtonContentGrid", typeof(Grid))]
+    [TemplatePart("DayText",           typeof(TextBlock))]
+    [TemplatePart("FirstSpacer",       typeof(Rectangle))]
+    [TemplatePart("FlyoutButton",      typeof(Button))]
+    [TemplatePart("MonthText",         typeof(TextBlock))]
+    [TemplatePart("PickerPresenter",   typeof(DatePickerPresenter))]
+    [TemplatePart("Popup",             typeof(Popup))]
+    [TemplatePart("SecondSpacer",      typeof(Rectangle))]
+    [TemplatePart("YearText",          typeof(TextBlock))]
     [PseudoClasses(":hasnodate")]
     public class DatePicker : TemplatedControl
     {

src/Avalonia.Controls/DateTimePickers/DatePickerPresenter.cs

@@ -1,4 +1,5 @@
-using Avalonia.Controls.Primitives;
+using Avalonia.Controls.Metadata;
+using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Shapes;
 using Avalonia.Input;
 using Avalonia.Interactivity;
@@ -12,6 +13,23 @@ namespace Avalonia.Controls
     /// Defines the presenter used for selecting a date for a 
     /// <see cref="DatePicker"/>
     /// </summary>
+    [TemplatePart("AcceptButton",    typeof(Button))]
+    [TemplatePart("DayDownButton",   typeof(RepeatButton))]
+    [TemplatePart("DayHost",         typeof(Panel))]
+    [TemplatePart("DaySelector",     typeof(DateTimePickerPanel))]
+    [TemplatePart("DayUpButton",     typeof(RepeatButton))]
+    [TemplatePart("DismissButton",   typeof(Button))]
+    [TemplatePart("FirstSpacer",     typeof(Rectangle))]
+    [TemplatePart("MonthDownButton", typeof(RepeatButton))]
+    [TemplatePart("MonthHost",       typeof(Panel))]
+    [TemplatePart("MonthSelector",   typeof(DateTimePickerPanel))]
+    [TemplatePart("MonthUpButton",   typeof(RepeatButton))]
+    [TemplatePart("PickerContainer", typeof(Grid))]
+    [TemplatePart("SecondSpacer",    typeof(Rectangle))]
+    [TemplatePart("YearDownButton",  typeof(RepeatButton))]
+    [TemplatePart("YearHost",        typeof(Panel))]
+    [TemplatePart("YearSelector",    typeof(DateTimePickerPanel))]
+    [TemplatePart("YearUpButton",    typeof(RepeatButton))]
     public class DatePickerPresenter : PickerPresenterBase
     {
         /// <summary>

src/Avalonia.Controls/DateTimePickers/DateTimePickerPanel.cs

@@ -1,7 +1,9 @@
 using System;
 using System.Globalization;
 using System.Linq;
+using Avalonia.Controls.Presenters;
 using Avalonia.Input;
+using Avalonia.Input.GestureRecognizers;
 using Avalonia.Interactivity;
 using Avalonia.Media;
 using Avalonia.VisualTree;
@@ -60,6 +62,7 @@ namespace Avalonia.Controls.Primitives
         private Vector _offset;
         private bool _hasInit;
         private bool _suppressUpdateOffset;
+        private ScrollContentPresenter? _parentScroller;
 
         public DateTimePickerPanel()
         {
@@ -255,6 +258,8 @@ namespace Avalonia.Controls.Primitives
                 _suppressUpdateOffset = true;
                 SelectedValue = (int)newSel * Increment + MinimumValue;
                 _suppressUpdateOffset = false;
+
+                System.Diagnostics.Debug.WriteLine($"Offset: {_offset} ItemHeight: {ItemHeight}");
             }
         }
 
@@ -270,7 +275,7 @@ namespace Avalonia.Controls.Primitives
 
         public Size Extent => _extent;
 
-        public Size Viewport => new Size(0, ItemHeight);
+        public Size Viewport => Bounds.Size;
 
         public event EventHandler? ScrollInvalidated;
 
@@ -341,6 +346,20 @@ namespace Avalonia.Controls.Primitives
             return finalSize;
         }
 
+        protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
+        {
+            base.OnAttachedToVisualTree(e);
+            _parentScroller = this.GetVisualParent() as ScrollContentPresenter;
+            _parentScroller?.AddHandler(Gestures.ScrollGestureEndedEvent, OnScrollGestureEnded);
+        }
+
+        protected override void OnDetachedFromVisualTree(VisualTreeAttachmentEventArgs e)
+        {
+            base.OnDetachedFromVisualTree(e);
+            _parentScroller?.RemoveHandler(Gestures.ScrollGestureEndedEvent, OnScrollGestureEnded);
+            _parentScroller = null;
+        }
+
         protected override void OnKeyDown(KeyEventArgs e)
         {
             switch (e.Key)
@@ -554,5 +573,15 @@ namespace Avalonia.Controls.Primitives
         {
             ScrollInvalidated?.Invoke(this, e);
         }
+
+        private void OnScrollGestureEnded(object? sender, ScrollGestureEndedEventArgs e)
+        {
+            var snapY = Math.Round(Offset.Y / ItemHeight) * ItemHeight;
+
+            if (snapY != Offset.Y)
+            {
+                Offset = Offset.WithY(snapY);
+            }
+        }
     }
 }

src/Avalonia.Controls/DateTimePickers/TimePicker.cs

@@ -12,6 +12,18 @@ namespace Avalonia.Controls
     /// <summary>
     /// A control to allow the user to select a time.
     /// </summary>
+    [TemplatePart("FirstColumnDivider",      typeof(Rectangle))]
+    [TemplatePart("FirstPickerHost",         typeof(Border))]
+    [TemplatePart("FlyoutButton",            typeof(Button))]
+    [TemplatePart("FlyoutButtonContentGrid", typeof(Grid))]
+    [TemplatePart("HourTextBlock",           typeof(TextBlock))]
+    [TemplatePart("MinuteTextBlock",         typeof(TextBlock))]
+    [TemplatePart("PeriodTextBlock",         typeof(TextBlock))]
+    [TemplatePart("PickerPresenter",         typeof(TimePickerPresenter))]
+    [TemplatePart("Popup",                   typeof(Popup))]
+    [TemplatePart("SecondColumnDivider",     typeof(Rectangle))]
+    [TemplatePart("SecondPickerHost",        typeof(Border))]
+    [TemplatePart("ThirdPickerHost",         typeof(Border))]
     [PseudoClasses(":hasnotime")]
     public class TimePicker : TemplatedControl
     {

src/Avalonia.Controls/DateTimePickers/TimePickerPresenter.cs

@@ -1,4 +1,5 @@
-using Avalonia.Controls.Primitives;
+using Avalonia.Controls.Metadata;
+using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Shapes;
 using Avalonia.Input;
 using Avalonia.Interactivity;
@@ -10,6 +11,20 @@ namespace Avalonia.Controls
     /// Defines the presenter used for selecting a time. Intended for use with
     /// <see cref="TimePicker"/> but can be used independently
     /// </summary>
+    [TemplatePart("AcceptButton",     typeof(Button))]
+    [TemplatePart("DismissButton",    typeof(Button))]
+    [TemplatePart("HourDownButton",   typeof(RepeatButton))]
+    [TemplatePart("HourSelector",     typeof(DateTimePickerPanel))]
+    [TemplatePart("HourUpButton",     typeof(RepeatButton))]
+    [TemplatePart("MinuteDownButton", typeof(RepeatButton))]
+    [TemplatePart("MinuteSelector",   typeof(DateTimePickerPanel))]
+    [TemplatePart("MinuteUpButton",   typeof(RepeatButton))]
+    [TemplatePart("PeriodDownButton", typeof(RepeatButton))]
+    [TemplatePart("PeriodHost",       typeof(Panel))]
+    [TemplatePart("PeriodSelector",   typeof(DateTimePickerPanel))]
+    [TemplatePart("PeriodUpButton",   typeof(RepeatButton))]
+    [TemplatePart("PickerContainer",  typeof(Grid))]
+    [TemplatePart("SecondSpacer",     typeof(Rectangle))]
     public class TimePickerPresenter : PickerPresenterBase
     {
         /// <summary>

src/Avalonia.Controls/Documents/TextElement.cs

@@ -13,37 +13,60 @@ namespace Avalonia.Controls.Documents
         /// Defines the <see cref="Background"/> property.
         /// </summary>
         public static readonly StyledProperty<IBrush?> BackgroundProperty =
-            AvaloniaProperty.Register<TextElement, IBrush?>(nameof(Background), inherits: true);
+            Border.BackgroundProperty.AddOwner<TextElement>();
 
         /// <summary>
         /// Defines the <see cref="FontFamily"/> property.
         /// </summary>
         public static readonly AttachedProperty<FontFamily> FontFamilyProperty =
-            TextBlock.FontFamilyProperty.AddOwner<TextElement>();
+            AvaloniaProperty.RegisterAttached<TextElement, Control, FontFamily>(
+                nameof(FontFamily),
+                defaultValue: FontFamily.Default,
+                inherits: true);
 
         /// <summary>
         /// Defines the <see cref="FontSize"/> property.
         /// </summary>
         public static readonly AttachedProperty<double> FontSizeProperty =
-            TextBlock.FontSizeProperty.AddOwner<TextElement>();
+            AvaloniaProperty.RegisterAttached<TextElement, Control, double>(
+                nameof(FontSize),
+                defaultValue: 12,
+                inherits: true);
 
         /// <summary>
         /// Defines the <see cref="FontStyle"/> property.
         /// </summary>
         public static readonly AttachedProperty<FontStyle> FontStyleProperty =
-            TextBlock.FontStyleProperty.AddOwner<TextElement>();
+            AvaloniaProperty.RegisterAttached<TextElement, Control, FontStyle>(
+                nameof(FontStyle),
+                inherits: true);
 
         /// <summary>
         /// Defines the <see cref="FontWeight"/> property.
         /// </summary>
         public static readonly AttachedProperty<FontWeight> FontWeightProperty =
-            TextBlock.FontWeightProperty.AddOwner<TextElement>();
+            AvaloniaProperty.RegisterAttached<TextElement, Control, FontWeight>(
+                nameof(FontWeight),
+                inherits: true,
+                defaultValue: FontWeight.Normal);
+
+        /// <summary>
+        /// Defines the <see cref="FontStretch"/> property.
+        /// </summary>
+        public static readonly AttachedProperty<FontStretch> FontStretchProperty =
+            AvaloniaProperty.RegisterAttached<TextElement, Control, FontStretch>(
+                nameof(FontStretch),
+                inherits: true,
+                defaultValue: FontStretch.Normal);
 
         /// <summary>
         /// Defines the <see cref="Foreground"/> property.
         /// </summary>
         public static readonly AttachedProperty<IBrush?> ForegroundProperty =
-            TextBlock.ForegroundProperty.AddOwner<TextElement>();
+            AvaloniaProperty.RegisterAttached<TextElement, Control, IBrush?>(
+                nameof(Foreground),
+                Brushes.Black,
+                inherits: true);
 
         /// <summary>
         /// Gets or sets a brush used to paint the control's background.
@@ -90,6 +113,15 @@ namespace Avalonia.Controls.Documents
             set { SetValue(FontWeightProperty, value); }
         }
 
+        /// <summary>
+        /// Gets or sets the font stretch.
+        /// </summary>
+        public FontStretch FontStretch
+        {
+            get { return GetValue(FontStretchProperty); }
+            set { SetValue(FontStretchProperty, value); }
+        }
+
         /// <summary>
         /// Gets or sets a brush used to paint the text.
         /// </summary>
@@ -98,7 +130,127 @@ namespace Avalonia.Controls.Documents
             get { return GetValue(ForegroundProperty); }
             set { SetValue(ForegroundProperty, value); }
         }
-        
+
+        /// <summary>
+        /// Gets the value of the attached <see cref="FontFamilyProperty"/> on a control.
+        /// </summary>
+        /// <param name="control">The control.</param>
+        /// <returns>The font family.</returns>
+        public static FontFamily GetFontFamily(Control control)
+        {
+            return control.GetValue(FontFamilyProperty);
+        }
+
+        /// <summary>
+        /// Sets the value of the attached <see cref="FontFamilyProperty"/> on a control.
+        /// </summary>
+        /// <param name="control">The control.</param>
+        /// <param name="value">The property value to set.</param>
+        public static void SetFontFamily(Control control, FontFamily value)
+        {
+            control.SetValue(FontFamilyProperty, value);
+        }
+
+        /// <summary>
+        /// Gets the value of the attached <see cref="FontSizeProperty"/> on a control.
+        /// </summary>
+        /// <param name="control">The control.</param>
+        /// <returns>The font size.</returns>
+        public static double GetFontSize(Control control)
+        {
+            return control.GetValue(FontSizeProperty);
+        }
+
+        /// <summary>
+        /// Sets the value of the attached <see cref="FontSizeProperty"/> on a control.
+        /// </summary>
+        /// <param name="control">The control.</param>
+        /// <param name="value">The property value to set.</param>
+        public static void SetFontSize(Control control, double value)
+        {
+            control.SetValue(FontSizeProperty, value);
+        }
+
+        /// <summary>
+        /// Gets the value of the attached <see cref="FontStyleProperty"/> on a control.
+        /// </summary>
+        /// <param name="control">The control.</param>
+        /// <returns>The font style.</returns>
+        public static FontStyle GetFontStyle(Control control)
+        {
+            return control.GetValue(FontStyleProperty);
+        }
+
+        /// <summary>
+        /// Sets the value of the attached <see cref="FontStyleProperty"/> on a control.
+        /// </summary>
+        /// <param name="control">The control.</param>
+        /// <param name="value">The property value to set.</param>
+        public static void SetFontStyle(Control control, FontStyle value)
+        {
+            control.SetValue(FontStyleProperty, value);
+        }
+
+        /// <summary>
+        /// Gets the value of the attached <see cref="FontWeightProperty"/> on a control.
+        /// </summary>
+        /// <param name="control">The control.</param>
+        /// <returns>The font weight.</returns>
+        public static FontWeight GetFontWeight(Control control)
+        {
+            return control.GetValue(FontWeightProperty);
+        }
+
+        /// <summary>
+        /// Sets the value of the attached <see cref="FontWeightProperty"/> on a control.
+        /// </summary>
+        /// <param name="control">The control.</param>
+        /// <param name="value">The property value to set.</param>
+        public static void SetFontWeight(Control control, FontWeight value)
+        {
+            control.SetValue(FontWeightProperty, value);
+        }
+
+        /// <summary>
+        /// Gets the value of the attached <see cref="FontStretchProperty"/> on a control.
+        /// </summary>
+        /// <param name="control">The control.</param>
+        /// <returns>The font stretch.</returns>
+        public static FontStretch GetFontStretch(Control control)
+        {
+            return control.GetValue(FontStretchProperty);
+        }
+
+        /// <summary>
+        /// Sets the value of the attached <see cref="FontStretchProperty"/> on a control.
+        /// </summary>
+        /// <param name="control">The control.</param>
+        /// <param name="value">The property value to set.</param>
+        public static void SetFontStretch(Control control, FontStretch value)
+        {
+            control.SetValue(FontStretchProperty, value);
+        }
+
+        /// <summary>
+        /// Gets the value of the attached <see cref="ForegroundProperty"/> on a control.
+        /// </summary>
+        /// <param name="control">The control.</param>
+        /// <returns>The foreground.</returns>
+        public static IBrush? GetForeground(Control control)
+        {
+            return control.GetValue(ForegroundProperty);
+        }
+
+        /// <summary>
+        /// Sets the value of the attached <see cref="ForegroundProperty"/> on a control.
+        /// </summary>
+        /// <param name="control">The control.</param>
+        /// <param name="value">The property value to set.</param>
+        public static void SetForeground(Control control, IBrush? value)
+        {
+            control.SetValue(ForegroundProperty, value);
+        }
+
         /// <summary>
         /// Raised when the visual representation of the text element changes.
         /// </summary>
@@ -115,6 +267,7 @@ namespace Avalonia.Controls.Documents
                 case nameof(FontSize):
                 case nameof(FontStyle):
                 case nameof(FontWeight):
+                case nameof(FontStretch):
                 case nameof(Foreground):
                     Invalidate();
                     break;

src/Avalonia.Controls/DropDown.cs

@@ -1,28 +0,0 @@
-using System;
-using Avalonia.Logging;
-using Avalonia.Styling;
-
-namespace Avalonia.Controls
-{
-    [Obsolete("Use ComboBox")]
-    public class DropDown : ComboBox, IStyleable
-    {
-        public DropDown()
-        {
-            Logger.TryGet(LogEventLevel.Warning, LogArea.Control)?.Log(this, "DropDown is deprecated: Use ComboBox");
-        }
-
-        Type IStyleable.StyleKey => typeof(ComboBox);
-    }
-
-    [Obsolete("Use ComboBoxItem")]
-    public class DropDownItem : ComboBoxItem, IStyleable
-    {
-        public DropDownItem()
-        {
-            Logger.TryGet(LogEventLevel.Warning, LogArea.Control)?.Log(this, "DropDownItem is deprecated: Use ComboBoxItem");
-        }
-
-        Type IStyleable.StyleKey => typeof(ComboBoxItem);
-    }
-}

src/Avalonia.Controls/DropDownButton.cs

@@ -0,0 +1,15 @@
+namespace Avalonia.Controls
+{
+    /// <summary>
+    /// A button with an added drop-down chevron to visually indicate it has a flyout with additional actions.
+    /// </summary>
+    public class DropDownButton : Button
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DropDownButton"/> class.
+        /// </summary>
+        public DropDownButton()
+        {
+        }
+    }
+}

src/Avalonia.Controls/Generators/ItemContainerGenerator.cs

@@ -82,7 +82,7 @@ namespace Avalonia.Controls.Generators
             {
                 var toMove = _containers.Where(x => x.Key >= index)
                     .OrderByDescending(x => x.Key)
-                    .ToList();
+                    .ToArray();
 
                 foreach (var i in toMove)
                 {
@@ -111,7 +111,7 @@ namespace Avalonia.Controls.Generators
                 }
 
                 var toMove = _containers.Where(x => x.Key >= startingIndex)
-                                        .OrderBy(x => x.Key).ToList();
+                                        .OrderBy(x => x.Key).ToArray();
 
                 foreach (var i in toMove)
                 {
@@ -122,9 +122,9 @@ namespace Avalonia.Controls.Generators
 
                 Dematerialized?.Invoke(this, new ItemContainerEventArgs(startingIndex, result));
 
-                if (toMove.Count > 0)
+                if (toMove.Length > 0)
                 {
-                    var containers = toMove.Select(x => x.Value).ToList();
+                    var containers = toMove.Select(x => x.Value).ToArray();
                     Recycled?.Invoke(this, new ItemContainerEventArgs(containers[0].Index, containers));
                 }
             }
@@ -138,10 +138,10 @@ namespace Avalonia.Controls.Generators
         /// <inheritdoc/>
         public virtual IEnumerable<ItemContainerInfo> Clear()
         {
-            var result = Containers.ToList();
+            var result = Containers.ToArray();
             _containers.Clear();
 
-            if (result.Count > 0)
+            if (result.Length > 0)
             {
                 Dematerialized?.Invoke(this, new ItemContainerEventArgs(0, result));
             }

src/Avalonia.Controls/HotkeyManager.cs

@@ -12,21 +12,61 @@ namespace Avalonia.Controls
 
         class HotkeyCommandWrapper : ICommand
         {
-            public HotkeyCommandWrapper(ICommandSource? control)
+            readonly WeakReference reference;
+
+            public HotkeyCommandWrapper(IControl control)
             {
-                CommandSource = control;
+                reference = new WeakReference(control);
             }
 
-            public readonly ICommandSource? CommandSource;
+            public ICommand? GetCommand()
+            {
+                if (reference.Target is { } target)
+                {
+                    if (target is ICommandSource commandSource && commandSource.Command is { } command)
+                    {
+                        return command;
+                    }
+                    else if (target is IClickableControl { })
+                    {
+                        return this;
+                    }
+                }
+                return null;
+            }
 
-            private ICommand? GetCommand() => CommandSource?.Command;
+            public bool CanExecute(object? parameter)
+            {
+                if (reference.Target is { } target)
+                {
+                    if (target is ICommandSource commandSource && commandSource.Command is { } command)
+                    {
+                        return commandSource.IsEffectivelyEnabled
+                            && command.CanExecute(commandSource.CommandParameter) == true;
+                    }
+                    else if (target is IClickableControl clickable)
+                    {
+                        return clickable.IsEffectivelyEnabled;
+                    }
+                }
+                return false;
+            }
 
-            public bool CanExecute(object? parameter) =>
+            public void Execute(object? parameter)
-                CommandSource?.Command?.CanExecute(CommandSource.CommandParameter) == true
+            {
-                && CommandSource.IsEffectivelyEnabled;
+                if (reference.Target is { } target)
+                {
+                    if (target is ICommandSource commandSource && commandSource.Command is { } command)
+                    {
+                        command.Execute(commandSource.CommandParameter);
+                    }
+                    else if (target is IClickableControl { IsEffectivelyEnabled: true } clickable)
+                    {
+                        clickable.RaiseClick();
+                    }
+                }
+            }
 
-            public void Execute(object? parameter) =>
-                GetCommand()?.Execute(CommandSource?.CommandParameter);
 
 #pragma warning disable 67 // Event not used
             public event EventHandler? CanExecuteChanged;
@@ -47,7 +87,7 @@ namespace Avalonia.Controls
             public Manager(IControl control)
             {
                 _control = control;
-                _wrapper = new HotkeyCommandWrapper(_control as ICommandSource);
+                _wrapper = new HotkeyCommandWrapper(_control);
             }
 
             public void Init()
@@ -104,13 +144,14 @@ namespace Avalonia.Controls
         {
             HotKeyProperty.Changed.Subscribe(args =>
             {
-                if (args.NewValue.Value is null) return;
+                if (args.NewValue.Value is null)
+                    return;
 
                 var control = args.Sender as IControl;
-                if (control is not ICommandSource)
+                if (control is not IClickableControl)
                 {
                     Logging.Logger.TryGet(Logging.LogEventLevel.Warning, Logging.LogArea.Control)?.Log(control,
-                        $"The element {args.Sender.GetType().Name} does not implement ICommandSource and does not support binding a HotKey ({args.NewValue}).");
+                        $"The element {args.Sender.GetType().Name} does not implement IClickableControl and does not support binding a HotKey ({args.NewValue}).");
                     return;
                 }
 

src/Avalonia.Controls/Image.cs

@@ -66,6 +66,8 @@ namespace Avalonia.Controls
             set { SetValue(StretchDirectionProperty, value); }
         }
 
+        protected override bool BypassFlowDirectionPolicies => true;
+        
         /// <summary>
         /// Renders the control.
         /// </summary>

src/Avalonia.Controls/ListBox.cs

@@ -1,5 +1,6 @@
 using System.Collections;
 using Avalonia.Controls.Generators;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Selection;
@@ -12,6 +13,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// An <see cref="ItemsControl"/> in which individual items can be selected.
     /// </summary>
+    [TemplatePart("PART_ScrollViewer", typeof(IScrollable))]
     public class ListBox : SelectingItemsControl
     {
         /// <summary>

src/Avalonia.Controls/MenuItem.cs

@@ -20,8 +20,9 @@ namespace Avalonia.Controls
     /// <summary>
     /// A menu item control.
     /// </summary>
+    [TemplatePart("PART_Popup", typeof(Popup))]
     [PseudoClasses(":separator", ":icon", ":open", ":pressed", ":selected")]
-    public class MenuItem : HeaderedSelectingItemsControl, IMenuItem, ISelectable, ICommandSource
+    public class MenuItem : HeaderedSelectingItemsControl, IMenuItem, ISelectable, ICommandSource, IClickableControl
     {
         /// <summary>
         /// Defines the <see cref="Command"/> property.
@@ -643,7 +644,9 @@ namespace Avalonia.Controls
         /// <param name="e">The property change event.</param>
         private void IsSelectedChanged(AvaloniaPropertyChangedEventArgs e)
         {
-            if ((bool)e.NewValue!)
+            var parentMenu = Parent as Menu;
+
+            if ((bool)e.NewValue! && (parentMenu is null || parentMenu.IsOpen))
             {
                 Focus();
             }
@@ -704,6 +707,14 @@ namespace Avalonia.Controls
 
         void ICommandSource.CanExecuteChanged(object sender, EventArgs e) => this.CanExecuteChanged(sender, e);
 
+        void IClickableControl.RaiseClick()
+        {
+            if (IsEffectivelyEnabled)
+            {
+                RaiseEvent(new RoutedEventArgs(ClickEvent));
+            }
+        }
+
         /// <summary>
         /// A dependency resolver which returns a <see cref="MenuItemAccessKeyHandler"/>.
         /// </summary>

src/Avalonia.Controls/Notifications/WindowNotificationManager.cs

@@ -14,6 +14,7 @@ namespace Avalonia.Controls.Notifications
     /// <summary>
     /// An <see cref="INotificationManager"/> that displays notifications in a <see cref="Window"/>.
     /// </summary>
+    [TemplatePart("PART_Items", typeof(Panel))]
     [PseudoClasses(":topleft", ":topright", ":bottomleft", ":bottomright")]
     public class WindowNotificationManager : TemplatedControl, IManagedNotificationManager, ICustomSimpleHitTest
     {

src/Avalonia.Controls/NumericUpDown/NumericUpDown.cs

@@ -2,6 +2,7 @@
 using System.Globalization;
 using System.IO;
 using System.Linq;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Data;
 using Avalonia.Input;
@@ -15,6 +16,8 @@ namespace Avalonia.Controls
     /// <summary>
     /// Control that represents a TextBox with button spinners that allow incrementing and decrementing numeric values.
     /// </summary>
+    [TemplatePart("PART_Spinner", typeof(Spinner))]
+    [TemplatePart("PART_TextBox", typeof(TextBox))]
     public class NumericUpDown : TemplatedControl
     {
         /// <summary>
@@ -1051,7 +1054,7 @@ namespace Avalonia.Controls
                         var currentValueTextSpecialCharacters = currentValueText.Where(c => !char.IsDigit(c));
                         var textSpecialCharacters = text.Where(c => !char.IsDigit(c));
                         // same non-digit characters on currentValueText and new text => remove them on new Text to parse it again.
-                        if (currentValueTextSpecialCharacters.Except(textSpecialCharacters).ToList().Count == 0)
+                        if (!currentValueTextSpecialCharacters.Except(textSpecialCharacters).Any())
                         {
                             foreach (var character in textSpecialCharacters)
                             {

src/Avalonia.Controls/Platform/DefaultMenuInteractionHandler.cs

@@ -149,13 +149,18 @@ namespace Avalonia.Controls.Platform
                 case Key.Up:
                 case Key.Down:
                 {
-                    if (item?.IsTopLevel == true)
+                    if (item?.IsTopLevel == true && item.HasSubMenu)
                     {
-                        if (item.HasSubMenu && !item.IsSubMenuOpen)
+                        if (!item.IsSubMenuOpen)
                         {
                             Open(item, true);
-                            e.Handled = true;
                         }
+                        else
+                        {
+                            item.MoveSelection(NavigationDirection.First, true);
+                        }
+
+                        e.Handled = true;
                     }
                     else
                     {
@@ -247,7 +252,8 @@ namespace Avalonia.Controls.Platform
                             // new menu.
                             if (item.IsSubMenuOpen &&
                                 item.Parent is IMenu &&
-                                item.Parent.SelectedItem is object)
+                                item.Parent.SelectedItem is object &&
+                                item.Parent.SelectedItem != item)
                             {
                                 item.Close();
                                 Open(item.Parent.SelectedItem, true);

src/Avalonia.Controls/Presenters/ContentPresenter.cs

@@ -1,5 +1,6 @@
 using System;
 
+using Avalonia.Controls.Documents;
 using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
@@ -46,7 +47,73 @@ namespace Avalonia.Controls.Presenters
         /// </summary>
         public static readonly StyledProperty<BoxShadows> BoxShadowProperty =
             Border.BoxShadowProperty.AddOwner<ContentPresenter>();
-        
+
+        /// <summary>
+        /// Defines the <see cref="Foreground"/> property.
+        /// </summary>
+        public static readonly AttachedProperty<IBrush?> ForegroundProperty =
+            TextElement.ForegroundProperty.AddOwner<ContentPresenter>();
+
+        /// <summary>
+        /// Defines the <see cref="FontFamily"/> property.
+        /// </summary>
+        public static readonly AttachedProperty<FontFamily> FontFamilyProperty =
+            TextElement.FontFamilyProperty.AddOwner<ContentPresenter>();
+
+        /// <summary>
+        /// Defines the <see cref="FontSize"/> property.
+        /// </summary>
+        public static readonly AttachedProperty<double> FontSizeProperty =
+            TextElement.FontSizeProperty.AddOwner<ContentPresenter>();
+
+        /// <summary>
+        /// Defines the <see cref="FontStyle"/> property.
+        /// </summary>
+        public static readonly AttachedProperty<FontStyle> FontStyleProperty =
+            TextElement.FontStyleProperty.AddOwner<ContentPresenter>();
+
+        /// <summary>
+        /// Defines the <see cref="FontWeight"/> property.
+        /// </summary>
+        public static readonly AttachedProperty<FontWeight> FontWeightProperty =
+            TextElement.FontWeightProperty.AddOwner<ContentPresenter>();
+
+        /// <summary>
+        /// Defines the <see cref="FontStretch"/> property.
+        /// </summary>
+        public static readonly AttachedProperty<FontStretch> FontStretchProperty =
+            TextElement.FontStretchProperty.AddOwner<ContentPresenter>();
+
+        /// <summary>
+        /// Defines the <see cref="TextAlignment"/> property
+        /// </summary>
+        public static readonly AttachedProperty<TextAlignment> TextAlignmentProperty =
+            TextBlock.TextAlignmentProperty.AddOwner<ContentPresenter>();
+
+        /// <summary>
+        /// Defines the <see cref="TextWrapping"/> property
+        /// </summary>
+        public static readonly AttachedProperty<TextWrapping> TextWrappingProperty =
+            TextBlock.TextWrappingProperty.AddOwner<ContentPresenter>();
+
+        /// <summary>
+        /// Defines the <see cref="TextTrimming"/> property
+        /// </summary>
+        public static readonly AttachedProperty<TextTrimming> TextTrimmingProperty =
+            TextBlock.TextTrimmingProperty.AddOwner<ContentPresenter>();
+
+        /// <summary>
+        /// Defines the <see cref="LineHeight"/> property
+        /// </summary>
+        public static readonly AttachedProperty<double> LineHeightProperty =
+            TextBlock.LineHeightProperty.AddOwner<ContentPresenter>();
+
+        /// <summary>
+        /// Defines the <see cref="MaxLines"/> property
+        /// </summary>
+        public static readonly AttachedProperty<int> MaxLinesProperty =
+            TextBlock.MaxLinesProperty.AddOwner<ContentPresenter>();
+                
         /// <summary>
         /// Defines the <see cref="Child"/> property.
         /// </summary>
@@ -159,6 +226,105 @@ namespace Avalonia.Controls.Presenters
             set => SetValue(BoxShadowProperty, value);
         }
 
+        /// <summary>
+        /// Gets or sets a brush used to paint the text.
+        /// </summary>
+        public IBrush? Foreground
+        {
+            get => GetValue(ForegroundProperty);
+            set => SetValue(ForegroundProperty, value);
+        }
+
+        /// <summary>
+        /// Gets or sets the font family.
+        /// </summary>
+        public FontFamily FontFamily
+        {
+            get => GetValue(FontFamilyProperty);
+            set => SetValue(FontFamilyProperty, value);
+        }
+
+        /// <summary>
+        /// Gets or sets the font size.
+        /// </summary>
+        public double FontSize
+        {
+            get => GetValue(FontSizeProperty);
+            set => SetValue(FontSizeProperty, value);
+        }
+
+        /// <summary>
+        /// Gets or sets the font style.
+        /// </summary>
+        public FontStyle FontStyle
+        {
+            get => GetValue(FontStyleProperty);
+            set => SetValue(FontStyleProperty, value);
+        }
+
+        /// <summary>
+        /// Gets or sets the font weight.
+        /// </summary>
+        public FontWeight FontWeight
+        {
+            get => GetValue(FontWeightProperty);
+            set => SetValue(FontWeightProperty, value);
+        }
+
+        /// <summary>
+        /// Gets or sets the font stretch.
+        /// </summary>
+        public FontStretch FontStretch
+        {
+            get => GetValue(FontStretchProperty);
+            set => SetValue(FontStretchProperty, value);
+        }
+
+        /// <summary>
+        /// Gets or sets the text alignment
+        /// </summary>
+        public TextAlignment TextAlignment
+        {
+            get => GetValue(TextAlignmentProperty);
+            set => SetValue(TextAlignmentProperty, value);
+        }
+
+        /// <summary>
+        /// Gets or sets the text wrapping
+        /// </summary>
+        public TextWrapping TextWrapping
+        {
+            get => GetValue(TextWrappingProperty);
+            set => SetValue(TextWrappingProperty, value);
+        }
+
+        /// <summary>
+        /// Gets or sets the text trimming
+        /// </summary>
+        public TextTrimming TextTrimming
+        {
+            get => GetValue(TextTrimmingProperty);
+            set => SetValue(TextTrimmingProperty, value);
+        }
+
+        /// <summary>
+        /// Gets or sets the line height
+        /// </summary>
+        public double LineHeight
+        {
+            get => GetValue(LineHeightProperty);
+            set => SetValue(LineHeightProperty, value);
+        }
+
+        /// <summary>
+        /// Gets or sets the max lines
+        /// </summary>
+        public int MaxLines
+        {
+            get => GetValue(MaxLinesProperty);
+            set => SetValue(MaxLinesProperty, value);
+        }
+
         /// <summary>
         /// Gets the control displayed by the presenter.
         /// </summary>

src/Avalonia.Controls/Presenters/ScrollContentPresenter.cs

@@ -389,7 +389,7 @@ namespace Avalonia.Controls.Presenters
                     {
                         var logicalUnits = delta.Y / logicalScrollItemSize.Y;
                         delta = delta.WithY(delta.Y - logicalUnits * logicalScrollItemSize.Y);
-                        dy = logicalUnits * scrollable!.ScrollSize.Height;
+                        dy = logicalUnits;
                     }
                     else
                         dy = delta.Y;
@@ -407,7 +407,7 @@ namespace Avalonia.Controls.Presenters
                     {
                         var logicalUnits = delta.X / logicalScrollItemSize.X;
                         delta = delta.WithX(delta.X - logicalUnits * logicalScrollItemSize.X);
-                        dx = logicalUnits * scrollable!.ScrollSize.Width;
+                        dx = logicalUnits;
                     }
                     else
                         dx = delta.X;

src/Avalonia.Controls/Presenters/TextPresenter.cs

@@ -8,6 +8,7 @@ using Avalonia.Utilities;
 using Avalonia.VisualTree;
 using Avalonia.Layout;
 using Avalonia.Media.Immutable;
+using Avalonia.Controls.Documents;
 
 namespace Avalonia.Controls.Presenters
 {
@@ -121,8 +122,8 @@ namespace Avalonia.Controls.Presenters
         /// </summary>
         public FontFamily FontFamily
         {
-            get => TextBlock.GetFontFamily(this);
+            get => TextElement.GetFontFamily(this);
-            set => TextBlock.SetFontFamily(this, value);
+            set => TextElement.SetFontFamily(this, value);
         }
 
         /// <summary>
@@ -130,8 +131,8 @@ namespace Avalonia.Controls.Presenters
         /// </summary>
         public double FontSize
         {
-            get => TextBlock.GetFontSize(this);
+            get => TextElement.GetFontSize(this);
-            set => TextBlock.SetFontSize(this, value);
+            set => TextElement.SetFontSize(this, value);
         }
 
         /// <summary>
@@ -139,8 +140,8 @@ namespace Avalonia.Controls.Presenters
         /// </summary>
         public FontStyle FontStyle
         {
-            get => TextBlock.GetFontStyle(this);
+            get => TextElement.GetFontStyle(this);
-            set => TextBlock.SetFontStyle(this, value);
+            set => TextElement.SetFontStyle(this, value);
         }
 
         /// <summary>
@@ -148,8 +149,8 @@ namespace Avalonia.Controls.Presenters
         /// </summary>
         public FontWeight FontWeight
         {
-            get => TextBlock.GetFontWeight(this);
+            get => TextElement.GetFontWeight(this);
-            set => TextBlock.SetFontWeight(this, value);
+            set => TextElement.SetFontWeight(this, value);
         }
 
         /// <summary>
@@ -157,8 +158,8 @@ namespace Avalonia.Controls.Presenters
         /// </summary>
         public FontStretch FontStretch
         {
-            get => TextBlock.GetFontStretch(this);
+            get => TextElement.GetFontStretch(this);
-            set => TextBlock.SetFontStretch(this, value);
+            set => TextElement.SetFontStretch(this, value);
         }
 
         /// <summary>
@@ -166,8 +167,8 @@ namespace Avalonia.Controls.Presenters
         /// </summary>
         public IBrush? Foreground
         {
-            get => TextBlock.GetForeground(this);
+            get => TextElement.GetForeground(this);
-            set => TextBlock.SetForeground(this, value);
+            set => TextElement.SetForeground(this, value);
         }
 
         /// <summary>
@@ -281,6 +282,8 @@ namespace Avalonia.Controls.Presenters
             }
         }
 
+        protected override bool BypassFlowDirectionPolicies => true;
+
         /// <summary>
         /// Creates the <see cref="TextLayout"/> used to render the text.
         /// </summary>
@@ -353,7 +356,7 @@ namespace Avalonia.Controls.Presenters
 
                 foreach (var rect in rects)
                 {
-                    context.FillRectangle(selectionBrush, rect);
+                    context.FillRectangle(selectionBrush, PixelRect.FromRect(rect, 1).ToRect(1));
                 }
             }
 
@@ -528,9 +531,9 @@ namespace Avalonia.Controls.Presenters
             {
                 return finalSize;
             }
-            
+
-            _constraint = finalSize;
+            _constraint = new Size(finalSize.Width, Math.Ceiling(finalSize.Height));
-                
+
             _textLayout = null;
 
             return finalSize;
@@ -637,14 +640,7 @@ namespace Avalonia.Controls.Presenters
             if (Text is null)
             {
                 return default;
-            }
+            }          
-            
-            if (FlowDirection == FlowDirection.RightToLeft)
-            {
-                direction = direction == LogicalDirection.Forward ?
-                    LogicalDirection.Backward :
-                    LogicalDirection.Forward;
-            }
 
             var characterHit = _lastCharacterHit;
             var caretIndex = characterHit.FirstCharacterIndex + characterHit.TrailingLength;
@@ -666,7 +662,7 @@ namespace Avalonia.Controls.Presenters
 
                     caretIndex = characterHit.FirstCharacterIndex + characterHit.TrailingLength;
 
-                    if (textLine.NewLineLength > 0 && caretIndex == textLine.TextRange.Start + textLine.TextRange.Length)
+                    if (textLine.NewLineLength > 0 && caretIndex == textLine.FirstTextSourceIndex + textLine.Length)
                     {
                         characterHit = new CharacterHit(caretIndex);
                     }
@@ -678,7 +674,7 @@ namespace Avalonia.Controls.Presenters
                         break;
                     }
 
-                    if (caretIndex - textLine.NewLineLength == textLine.TextRange.Start + textLine.TextRange.Length)
+                    if (caretIndex - textLine.NewLineLength == textLine.FirstTextSourceIndex + textLine.Length)
                     {
                         break;
                     }
@@ -719,6 +715,13 @@ namespace Avalonia.Controls.Presenters
         
         public void MoveCaretHorizontal(LogicalDirection direction = LogicalDirection.Forward)
         {
+            if (FlowDirection == FlowDirection.RightToLeft)
+            {
+                direction = direction == LogicalDirection.Forward ?
+                    LogicalDirection.Backward :
+                    LogicalDirection.Forward;
+            }
+
             var characterHit = GetNextCharacterHit(direction);
 
             UpdateCaret(characterHit);
@@ -779,19 +782,25 @@ namespace Avalonia.Controls.Presenters
             
             switch (change.Property.Name)
             {
-                case nameof (TextBlock.Foreground):
+                case nameof (Foreground):
-                case nameof (TextBlock.FontSize):
+                case nameof (FontSize):
-                case nameof (TextBlock.FontStyle):
+                case nameof (FontStyle):
-                case nameof (TextBlock.FontWeight):
+                case nameof (FontWeight):
-                case nameof (TextBlock.FontFamily):
+                case nameof (FontFamily):
+                case nameof (FontStretch):
+
                 case nameof (Text):
                 case nameof (TextAlignment):
                 case nameof (TextWrapping):
+
                 case nameof (SelectionStart):
                 case nameof (SelectionEnd):
                 case nameof (SelectionForegroundBrush):
+
                 case nameof (PasswordChar):
                 case nameof (RevealPassword):
+
+                case nameof(FlowDirection):
                 {
                     InvalidateTextLayout();
                     break;

src/Avalonia.Controls/Primitives/OverlayPopupHost.cs

@@ -76,7 +76,7 @@ namespace Avalonia.Controls.Primitives
             Rect? rect = null)
         {
             _positionerParameters.ConfigurePosition((TopLevel)_overlayLayer.GetVisualRoot()!, target, placement, offset, anchor,
-                gravity, constraintAdjustment, rect);
+                gravity, constraintAdjustment, rect, FlowDirection);
             UpdatePosition();
         }
 

src/Avalonia.Controls/Primitives/PopupPositioning/IPopupPositioner.cs

@@ -46,6 +46,7 @@ Copyright © 2019 Nikita Tsukanov
 
 using System;
 using Avalonia.VisualTree;
+using Avalonia.Media;
 
 namespace Avalonia.Controls.Primitives.PopupPositioning
 {
@@ -444,7 +445,8 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
             TopLevel topLevel,
             IVisual target, PlacementMode placement, Point offset,
             PopupAnchor anchor, PopupGravity gravity,
-            PopupPositionerConstraintAdjustment constraintAdjustment, Rect? rect)
+            PopupPositionerConstraintAdjustment constraintAdjustment, Rect? rect,
+            FlowDirection flowDirection)
         {
             // We need a better way for tracking the last pointer position
 #pragma warning disable CS0618 // Type or member is obsolete
@@ -503,6 +505,32 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
                 else
                     throw new InvalidOperationException("Invalid value for Popup.PlacementMode");
             }
+
+            // Invert coordinate system if FlowDirection is RTL
+            if (flowDirection == FlowDirection.RightToLeft)
+            {
+                if ((positionerParameters.Anchor & PopupAnchor.Right) == PopupAnchor.Right)
+                {
+                    positionerParameters.Anchor ^= PopupAnchor.Right;
+                    positionerParameters.Anchor |= PopupAnchor.Left;
+                }
+                else if ((positionerParameters.Anchor & PopupAnchor.Left) == PopupAnchor.Left)
+                {
+                    positionerParameters.Anchor ^= PopupAnchor.Left;
+                    positionerParameters.Anchor |= PopupAnchor.Right;
+                }
+
+                if ((positionerParameters.Gravity & PopupGravity.Right) == PopupGravity.Right)
+                {
+                    positionerParameters.Gravity ^= PopupGravity.Right;
+                    positionerParameters.Gravity |= PopupGravity.Left;
+                }
+                else if ((positionerParameters.Gravity & PopupGravity.Left) == PopupGravity.Left)
+                {
+                    positionerParameters.Gravity ^= PopupGravity.Left;
+                    positionerParameters.Gravity |= PopupGravity.Right;
+                }
+            }
         }
     }
 

src/Avalonia.Controls/Primitives/PopupPositioning/ManagedPopupPositionerPopupImplHelper.cs

@@ -23,8 +23,9 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
 
         public IReadOnlyList<ManagedPopupPositionerScreenInfo> Screens =>
 
-            _parent.Screen.AllScreens.Select(s => new ManagedPopupPositionerScreenInfo(
+            _parent.Screen.AllScreens
-                s.Bounds.ToRect(1), s.WorkingArea.ToRect(1))).ToList();
+                .Select(s => new ManagedPopupPositionerScreenInfo(s.Bounds.ToRect(1), s.WorkingArea.ToRect(1)))
+                .ToArray();
 
         public Rect ParentClientAreaScreenGeometry
         {

src/Avalonia.Controls/Primitives/PopupRoot.cs

@@ -17,7 +17,6 @@ namespace Avalonia.Controls.Primitives
     /// </summary>
     public sealed class PopupRoot : WindowBase, IInteractive, IHostedVisualTreeRoot, IDisposable, IStyleHost, IPopupHost
     {
-        private readonly TopLevel _parent;
         private PopupPositionerParameters _positionerParameters;        
 
         /// <summary>
@@ -47,7 +46,7 @@ namespace Avalonia.Controls.Primitives
         public PopupRoot(TopLevel parent, IPopupImpl impl, IAvaloniaDependencyResolver? dependencyResolver)
             : base(impl, dependencyResolver)
         {
-            _parent = parent;
+            ParentTopLevel = parent;
         }
 
         /// <summary>
@@ -73,6 +72,8 @@ namespace Avalonia.Controls.Primitives
         /// </summary>
         IStyleHost? IStyleHost.StylingParent => Parent;
 
+        public TopLevel ParentTopLevel { get; }
+
         /// <inheritdoc/>
         public void Dispose()
         {
@@ -91,8 +92,8 @@ namespace Avalonia.Controls.Primitives
             PopupPositionerConstraintAdjustment constraintAdjustment = PopupPositionerConstraintAdjustment.All,
             Rect? rect = null)
         {
-            _positionerParameters.ConfigurePosition(_parent, target,
+            _positionerParameters.ConfigurePosition(ParentTopLevel, target,
-                placement, offset, anchor, gravity, constraintAdjustment, rect);
+                placement, offset, anchor, gravity, constraintAdjustment, rect, FlowDirection);
 
             if (_positionerParameters.Size != default)
                 UpdatePosition();

src/Avalonia.Controls/Primitives/ScrollBar.cs

@@ -22,6 +22,10 @@ namespace Avalonia.Controls.Primitives
     /// <summary>
     /// A scrollbar control.
     /// </summary>
+    [TemplatePart("PART_LineDownButton", typeof(Button))]
+    [TemplatePart("PART_LineUpButton",   typeof(Button))]
+    [TemplatePart("PART_PageDownButton", typeof(Button))]
+    [TemplatePart("PART_PageUpButton",   typeof(Button))]
     [PseudoClasses(":vertical", ":horizontal")]
     public class ScrollBar : RangeBase
     {

src/Avalonia.Controls/Primitives/SelectingItemsControl.cs

@@ -292,11 +292,11 @@ namespace Avalonia.Controls.Primitives
                             "collection is different to the Items on the control.");
                     }
 
-                    var oldSelection = _selection?.SelectedItems.ToList();
+                    var oldSelection = _selection?.SelectedItems.ToArray();
                     DeinitializeSelectionModel(_selection);
                     _selection = value;
 
-                    if (oldSelection?.Count > 0)
+                    if (oldSelection?.Length > 0)
                     {
                         RaiseEvent(new SelectionChangedEventArgs(
                             SelectionChangedEvent,
@@ -845,8 +845,8 @@ namespace Avalonia.Controls.Primitives
             {
                 var ev = new SelectionChangedEventArgs(
                     SelectionChangedEvent,
-                    e.DeselectedItems.ToList(),
+                    e.DeselectedItems.ToArray(),
-                    e.SelectedItems.ToList());
+                    e.SelectedItems.ToArray());
                 RaiseEvent(ev);
             }
         }
@@ -988,7 +988,7 @@ namespace Avalonia.Controls.Primitives
                 RaiseEvent(new SelectionChangedEventArgs(
                     SelectionChangedEvent,
                     Array.Empty<object>(),
-                    Selection.SelectedItems.ToList()));
+                    Selection.SelectedItems.ToArray()));
             }
         }
 

src/Avalonia.Controls/Primitives/TemplatedControl.cs

@@ -1,4 +1,5 @@
 using System;
+using Avalonia.Controls.Documents;
 using Avalonia.Controls.Templates;
 using Avalonia.Interactivity;
 using Avalonia.Logging;
@@ -41,31 +42,37 @@ namespace Avalonia.Controls.Primitives
         /// Defines the <see cref="FontFamily"/> property.
         /// </summary>
         public static readonly StyledProperty<FontFamily> FontFamilyProperty =
-            TextBlock.FontFamilyProperty.AddOwner<TemplatedControl>();
+            TextElement.FontFamilyProperty.AddOwner<TemplatedControl>();
 
         /// <summary>
         /// Defines the <see cref="FontSize"/> property.
         /// </summary>
         public static readonly StyledProperty<double> FontSizeProperty =
-            TextBlock.FontSizeProperty.AddOwner<TemplatedControl>();
+            TextElement.FontSizeProperty.AddOwner<TemplatedControl>();
 
         /// <summary>
         /// Defines the <see cref="FontStyle"/> property.
         /// </summary>
         public static readonly StyledProperty<FontStyle> FontStyleProperty =
-            TextBlock.FontStyleProperty.AddOwner<TemplatedControl>();
+            TextElement.FontStyleProperty.AddOwner<TemplatedControl>();
 
         /// <summary>
         /// Defines the <see cref="FontWeight"/> property.
         /// </summary>
         public static readonly StyledProperty<FontWeight> FontWeightProperty =
-            TextBlock.FontWeightProperty.AddOwner<TemplatedControl>();
+            TextElement.FontWeightProperty.AddOwner<TemplatedControl>();
+
+        /// <summary>
+        /// Defines the <see cref="FontWeight"/> property.
+        /// </summary>
+        public static readonly StyledProperty<FontStretch> FontStretchProperty =
+            TextElement.FontStretchProperty.AddOwner<TemplatedControl>();
 
         /// <summary>
         /// Defines the <see cref="Foreground"/> property.
         /// </summary>
         public static readonly StyledProperty<IBrush?> ForegroundProperty =
-            TextBlock.ForegroundProperty.AddOwner<TemplatedControl>();
+            TextElement.ForegroundProperty.AddOwner<TemplatedControl>();
 
         /// <summary>
         /// Defines the <see cref="Padding"/> property.
@@ -185,6 +192,15 @@ namespace Avalonia.Controls.Primitives
             set { SetValue(FontWeightProperty, value); }
         }
 
+        /// <summary>
+        /// Gets or sets the font stretch used to draw the control's text.
+        /// </summary>
+        public FontStretch FontStretch
+        {
+            get { return GetValue(FontStretchProperty); }
+            set { SetValue(FontStretchProperty, value); }
+        }
+
         /// <summary>
         /// Gets or sets the brush used to draw the control's text and other foreground elements.
         /// </summary>
@@ -340,6 +356,11 @@ namespace Avalonia.Controls.Primitives
             base.OnDetachedFromLogicalTree(e);
         }
 
+        /// <summary>
+        /// Called when the control's template is applied.
+        /// In simple terms, this means the method is called just before the control is displayed.
+        /// </summary>
+        /// <param name="e">The event args.</param>
         protected virtual void OnApplyTemplate(TemplateAppliedEventArgs e)
         {
         }

src/Avalonia.Controls/ProgressBar.cs

@@ -10,6 +10,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// A control used to indicate the progress of an operation.
     /// </summary>
+    [TemplatePart("PART_Indicator", typeof(Border))]
     [PseudoClasses(":vertical", ":horizontal", ":indeterminate")]
     public class ProgressBar : RangeBase
     {

src/Avalonia.Controls/ScrollViewer.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Reactive.Linq;
 using Avalonia.Automation.Peers;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Primitives;
 using Avalonia.Input;
@@ -11,6 +12,8 @@ namespace Avalonia.Controls
     /// <summary>
     /// A control which scrolls its content if the content is bigger than the space available.
     /// </summary>
+    [TemplatePart("PART_HorizontalScrollBar", typeof(ScrollBar))]
+    [TemplatePart("PART_VerticalScrollBar",   typeof(ScrollBar))]
     public class ScrollViewer : ContentControl, IScrollable, IScrollAnchorProvider
     {
         /// <summary>

src/Avalonia.Controls/Selection/InternalSelectionModel.cs

@@ -182,8 +182,8 @@ namespace Avalonia.Controls.Selection
             try
             {
                 var items = WritableSelectedItems;
-                var deselected = e.DeselectedItems.ToList();
+                var deselected = e.DeselectedItems.ToArray();
-                var selected = e.SelectedItems.ToList();
+                var selected = e.SelectedItems.ToArray();
 
                 _ignoreSelectedItemsChanges = true;
 

src/Avalonia.Controls/Shapes/Rectangle.cs

@@ -2,19 +2,139 @@ using Avalonia.Media;
 
 namespace Avalonia.Controls.Shapes
 {
+    /// <summary>
+    /// Represents a rectangle with optional rounded corners.
+    /// </summary>
     public class Rectangle : Shape
     {
+        private const double PiOver2 = 1.57079633; // 90 deg to rad
+
+        /// <summary>
+        /// Defines the <see cref="RadiusX"/> property.
+        /// </summary>
+        public static readonly StyledProperty<double> RadiusXProperty =
+            AvaloniaProperty.Register<Rectangle, double>(nameof(RadiusX));
+
+        /// <summary>
+        /// Defines the <see cref="RadiusY"/> property.
+        /// </summary>
+        public static readonly StyledProperty<double> RadiusYProperty =
+            AvaloniaProperty.Register<Rectangle, double>(nameof(RadiusY));
+
         static Rectangle()
         {
-            AffectsGeometry<Rectangle>(BoundsProperty, StrokeThicknessProperty);
+            AffectsGeometry<Rectangle>(
+                BoundsProperty,
+                RadiusXProperty,
+                RadiusYProperty,
+                StrokeThicknessProperty);
+        }
+
+        /// <summary>
+        /// Gets or sets the radius on the X-axis used to round the corners of the rectangle.
+        /// Corner radii are represented by an ellipse so this is the X-axis width of the ellipse.
+        /// </summary>
+        public double RadiusX
+        {
+            get => GetValue(RadiusXProperty);
+            set => SetValue(RadiusXProperty, value);
+        }
+
+        /// <summary>
+        /// Gets or sets the radius on the Y-axis used to round the corners of the rectangle.
+        /// Corner radii are represented by an ellipse so this is the Y-axis height of the ellipse.
+        /// </summary>
+        public double RadiusY
+        {
+            get => GetValue(RadiusYProperty);
+            set => SetValue(RadiusYProperty, value);
         }
 
+        /// <inheritdoc/>
         protected override Geometry CreateDefiningGeometry()
         {
-            var rect = new Rect(Bounds.Size).Deflate(StrokeThickness / 2);
+            // TODO: If RectangleGeometry ever supports RadiusX/Y like in WPF,
-            return new RectangleGeometry(rect);
+            // this code can be removed/combined with that implementation
+
+            double x = RadiusX;
+            double y = RadiusY;
+
+            if (x == 0 && y == 0)
+            {
+                // Optimization when there are no corner radii
+                var rect = new Rect(Bounds.Size).Deflate(StrokeThickness / 2);
+                return new RectangleGeometry(rect);
+            }
+            else
+            {
+                var rect = new Rect(Bounds.Size).Deflate(StrokeThickness / 2);
+                var geometry = new StreamGeometry();
+                var arcSize = new Size(x, y);
+
+                using (StreamGeometryContext context = geometry.Open())
+                {
+                    // The rectangle is constructed as follows:
+                    //
+                    //   (origin)
+                    //   Corner 4            Corner 1
+                    //   Top/Left  Line 1    Top/Right
+                    //      \_   __________   _/
+                    //          |          |
+                    //   Line 4 |          | Line 2
+                    //       _  |__________|  _
+                    //      /      Line 3      \
+                    //   Corner 3            Corner 2
+                    //   Bottom/Left         Bottom/Right
+                    //
+                    // - Lines 1,3 follow the deflated rectangle bounds minus RadiusX
+                    // - Lines 2,4 follow the deflated rectangle bounds minus RadiusY
+                    // - All corners are constructed using elliptical arcs 
+
+                    // Line 1 + Corner 1
+                    context.BeginFigure(new Point(rect.Left + x, rect.Top), true);
+                    context.LineTo(new Point(rect.Right - x, rect.Top));
+                    context.ArcTo(
+                        new Point(rect.Right, rect.Top + y),
+                        arcSize,
+                        rotationAngle: PiOver2,
+                        isLargeArc: false,
+                        SweepDirection.Clockwise);
+
+                    // Line 2 + Corner 2
+                    context.LineTo(new Point(rect.Right, rect.Bottom - y));
+                    context.ArcTo(
+                        new Point(rect.Right - x, rect.Bottom),
+                        arcSize,
+                        rotationAngle: PiOver2,
+                        isLargeArc: false,
+                        SweepDirection.Clockwise);
+
+                    // Line 3 + Corner 3
+                    context.LineTo(new Point(rect.Left + x, rect.Bottom));
+                    context.ArcTo(
+                        new Point(rect.Left, rect.Bottom - y),
+                        arcSize,
+                        rotationAngle: PiOver2,
+                        isLargeArc: false,
+                        SweepDirection.Clockwise);
+
+                    // Line 4 + Corner 4
+                    context.LineTo(new Point(rect.Left, rect.Top + y));
+                    context.ArcTo(
+                        new Point(rect.Left + x, rect.Top),
+                        arcSize,
+                        rotationAngle: PiOver2,
+                        isLargeArc: false,
+                        SweepDirection.Clockwise);
+
+                    context.EndFigure(true);
+                }
+
+                return geometry;
+            }
         }
 
+        /// <inheritdoc/>
         protected override Size MeasureOverride(Size availableSize)
         {
             return new Size(StrokeThickness, StrokeThickness);

src/Avalonia.Controls/Slider.cs

@@ -42,6 +42,9 @@ namespace Avalonia.Controls
     /// <summary>
     /// A control that lets the user select from a range of values by moving a Thumb control along a Track.
     /// </summary>
+    [TemplatePart("PART_DecreaseButton", typeof(Button))]
+    [TemplatePart("PART_IncreaseButton", typeof(Button))]
+    [TemplatePart("PART_Track",          typeof(Track))]
     [PseudoClasses(":vertical", ":horizontal", ":pressed")]
     public class Slider : RangeBase
     {

src/Avalonia.Controls/SplitButton/SplitButton.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Windows.Input;
 using Avalonia.Controls.Metadata;
-using Avalonia.Controls.Mixins;
 using Avalonia.Controls.Primitives;
 using Avalonia.Input;
 using Avalonia.Interactivity;
@@ -13,6 +12,8 @@ namespace Avalonia.Controls
     /// A button with primary and secondary parts that can each be pressed separately.
     /// The primary part behaves like a <see cref="Button"/> and the secondary part opens a flyout.
     /// </summary>
+    [TemplatePart("PART_PrimaryButton",   typeof(Button))]
+    [TemplatePart("PART_SecondaryButton", typeof(Button))]
     [PseudoClasses(pcFlyoutOpen, pcPressed)]
     public class SplitButton : ContentControl, ICommandSource
     {
@@ -314,16 +315,9 @@ namespace Avalonia.Controls
                 }
 
                 // Must unregister events here while a reference to the old flyout still exists
-                if (oldFlyout != null)
+                UnregisterFlyoutEvents(oldFlyout);
-                {
-                    UnregisterFlyoutEvents(oldFlyout);
-                }
-
-                if (newFlyout != null)
-                {
-                    RegisterFlyoutEvents(newFlyout);
-                }
 
+                RegisterFlyoutEvents(newFlyout);
                 UpdatePseudoClasses();
             }
 
@@ -415,6 +409,22 @@ namespace Avalonia.Controls
             }
         }
 
+        /// <summary>
+        /// Invoked when the split button's flyout is opened.
+        /// </summary>
+        protected virtual void OnFlyoutOpened()
+        {
+            // Available for derived types
+        }
+
+        /// <summary>
+        /// Invoked when the split button's flyout is closed.
+        /// </summary>
+        protected virtual void OnFlyoutClosed()
+        {
+            // Available for derived types
+        }
+
         ////////////////////////////////////////////////////////////////////////
         // Event Handling
         ////////////////////////////////////////////////////////////////////////
@@ -464,6 +474,8 @@ namespace Avalonia.Controls
             {
                 _isFlyoutOpen = true;
                 UpdatePseudoClasses();
+
+                OnFlyoutOpened();
             }
         }
 
@@ -479,6 +491,8 @@ namespace Avalonia.Controls
             {
                 _isFlyoutOpen = false;
                 UpdatePseudoClasses();
+
+                OnFlyoutClosed();
             }
         }
     }

src/Avalonia.Controls/SplitView.cs

@@ -77,6 +77,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// A control with two views: A collapsible pane and an area for content
     /// </summary>
+    [TemplatePart("PART_PaneRoot", typeof(Panel))]
     [PseudoClasses(":open", ":closed")]
     [PseudoClasses(":compactoverlay", ":compactinline", ":overlay", ":inline")]
     [PseudoClasses(":left", ":right")]

src/Avalonia.Controls/TabControl.cs

@@ -11,12 +11,14 @@ using Avalonia.Layout;
 using Avalonia.LogicalTree;
 using Avalonia.VisualTree;
 using Avalonia.Automation;
+using Avalonia.Controls.Metadata;
 
 namespace Avalonia.Controls
 {
     /// <summary>
     /// A tab control that displays a tab strip along with the content of the selected tab.
     /// </summary>
+    [TemplatePart("PART_ItemsPresenter", typeof(ItemsPresenter))]
     public class TabControl : SelectingItemsControl, IContentPresenterHost
     {
         /// <summary>

src/Avalonia.Controls/TextBlock.cs

@@ -28,78 +28,69 @@ namespace Avalonia.Controls
         public static readonly StyledProperty<Thickness> PaddingProperty =
             Decorator.PaddingProperty.AddOwner<TextBlock>();
 
-        // TODO: Define these attached properties elsewhere (e.g. on a Text class) and AddOwner
-        // them into TextBlock.
-
         /// <summary>
         /// Defines the <see cref="FontFamily"/> property.
         /// </summary>
-        public static readonly AttachedProperty<FontFamily> FontFamilyProperty =
+        public static readonly StyledProperty<FontFamily> FontFamilyProperty =
-            AvaloniaProperty.RegisterAttached<TextBlock, Control, FontFamily>(
+            TextElement.FontFamilyProperty.AddOwner<TextBlock>();
-                nameof(FontFamily),
-                defaultValue: FontFamily.Default,
-                inherits: true);
 
         /// <summary>
         /// Defines the <see cref="FontSize"/> property.
         /// </summary>
-        public static readonly AttachedProperty<double> FontSizeProperty =
+        public static readonly StyledProperty<double> FontSizeProperty =
-            AvaloniaProperty.RegisterAttached<TextBlock, Control, double>(
+            TextElement.FontSizeProperty.AddOwner<TextBlock>();
-                nameof(FontSize),
-                defaultValue: 12,
-                inherits: true);
 
         /// <summary>
         /// Defines the <see cref="FontStyle"/> property.
         /// </summary>
-        public static readonly AttachedProperty<FontStyle> FontStyleProperty =
+        public static readonly StyledProperty<FontStyle> FontStyleProperty =
-            AvaloniaProperty.RegisterAttached<TextBlock, Control, FontStyle>(
+            TextElement.FontStyleProperty.AddOwner<TextBlock>();
-                nameof(FontStyle),
-                inherits: true);
 
         /// <summary>
         /// Defines the <see cref="FontWeight"/> property.
         /// </summary>
-        public static readonly AttachedProperty<FontWeight> FontWeightProperty =
+        public static readonly StyledProperty<FontWeight> FontWeightProperty =
-            AvaloniaProperty.RegisterAttached<TextBlock, Control, FontWeight>(
+            TextElement.FontWeightProperty.AddOwner<TextBlock>();
-                nameof(FontWeight),
-                inherits: true,
-                defaultValue: FontWeight.Normal);
 
         /// <summary>
-        /// Defines the <see cref="FontStretch"/> property.
+        /// Defines the <see cref="FontWeight"/> property.
         /// </summary>
-        public static readonly AttachedProperty<FontStretch> FontStretchProperty =
+        public static readonly StyledProperty<FontStretch> FontStretchProperty =
-            AvaloniaProperty.RegisterAttached<TextBlock, Control, FontStretch>(
+            TextElement.FontStretchProperty.AddOwner<TextBlock>();
-                nameof(FontStretch),
+
-                inherits: true,
-                defaultValue: FontStretch.Normal);
-        
         /// <summary>
         /// Defines the <see cref="Foreground"/> property.
         /// </summary>
-        public static readonly AttachedProperty<IBrush?> ForegroundProperty =
+        public static readonly StyledProperty<IBrush?> ForegroundProperty =
-            AvaloniaProperty.RegisterAttached<TextBlock, Control, IBrush?>(
+            TextElement.ForegroundProperty.AddOwner<TextBlock>();
-                nameof(Foreground),
+
-                Brushes.Black,
+        /// <summary>
-                inherits: true);
+        /// DependencyProperty for <see cref="BaselineOffset" /> property.
+        /// </summary>
+        public static readonly AttachedProperty<double> BaselineOffsetProperty =
+            AvaloniaProperty.RegisterAttached<TextBlock, Control, double>(
+                nameof(BaselineOffset),
+                0,
+                true);
 
         /// <summary>
         /// Defines the <see cref="LineHeight"/> property.
         /// </summary>
-        public static readonly StyledProperty<double> LineHeightProperty =
+        public static readonly AttachedProperty<double> LineHeightProperty =
-            AvaloniaProperty.Register<TextBlock, double>(
+            AvaloniaProperty.RegisterAttached<TextBlock, Control, double>(
                 nameof(LineHeight),
                 double.NaN,
-                validate: IsValidLineHeight);
+                validate: IsValidLineHeight,
+                inherits: true);
 
         /// <summary>
         /// Defines the <see cref="MaxLines"/> property.
         /// </summary>
-        public static readonly StyledProperty<int> MaxLinesProperty =
+        public static readonly AttachedProperty<int> MaxLinesProperty =
-            AvaloniaProperty.Register<TextBlock, int>(
+            AvaloniaProperty.RegisterAttached<TextBlock, Control, int>(
                 nameof(MaxLines),
-                validate: IsValidMaxLines);
+                validate: IsValidMaxLines,
+                inherits: true);
 
         /// <summary>
         /// Defines the <see cref="Text"/> property.
@@ -121,20 +112,24 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="TextAlignment"/> property.
         /// </summary>
-        public static readonly StyledProperty<TextAlignment> TextAlignmentProperty =
+        public static readonly AttachedProperty<TextAlignment> TextAlignmentProperty =
-            AvaloniaProperty.Register<TextBlock, TextAlignment>(nameof(TextAlignment));
+            AvaloniaProperty.RegisterAttached<TextBlock, Control, TextAlignment>(nameof(TextAlignment), 
+                inherits: true);
 
         /// <summary>
         /// Defines the <see cref="TextWrapping"/> property.
         /// </summary>
-        public static readonly StyledProperty<TextWrapping> TextWrappingProperty =
+        public static readonly AttachedProperty<TextWrapping> TextWrappingProperty =
-            AvaloniaProperty.Register<TextBlock, TextWrapping>(nameof(TextWrapping));
+            AvaloniaProperty.RegisterAttached<TextBlock, Control, TextWrapping>(nameof(TextWrapping), 
+                inherits: true);
 
         /// <summary>
         /// Defines the <see cref="TextTrimming"/> property.
         /// </summary>
-        public static readonly StyledProperty<TextTrimming> TextTrimmingProperty =
+        public static readonly AttachedProperty<TextTrimming> TextTrimmingProperty =
-            AvaloniaProperty.Register<TextBlock, TextTrimming>(nameof(TextTrimming), defaultValue: TextTrimming.None);
+            AvaloniaProperty.RegisterAttached<TextBlock, Control, TextTrimming>(nameof(TextTrimming), 
+                defaultValue: TextTrimming.None,
+                inherits: true);
 
         /// <summary>
         /// Defines the <see cref="TextDecorations"/> property.
@@ -222,7 +217,7 @@ namespace Avalonia.Controls
         public InlineCollection Inlines { get; }
 
         /// <summary>
-        /// Gets or sets the font family.
+        /// Gets or sets the font family used to draw the control's text.
         /// </summary>
         public FontFamily FontFamily
         {
@@ -231,7 +226,7 @@ namespace Avalonia.Controls
         }
 
         /// <summary>
-        /// Gets or sets the font size.
+        /// Gets or sets the size of the control's text in points.
         /// </summary>
         public double FontSize
         {
@@ -240,7 +235,7 @@ namespace Avalonia.Controls
         }
 
         /// <summary>
-        /// Gets or sets the font style.
+        /// Gets or sets the font style used to draw the control's text.
         /// </summary>
         public FontStyle FontStyle
         {
@@ -249,16 +244,16 @@ namespace Avalonia.Controls
         }
 
         /// <summary>
-        /// Gets or sets the font weight.
+        /// Gets or sets the font weight used to draw the control's text.
         /// </summary>
         public FontWeight FontWeight
         {
             get { return GetValue(FontWeightProperty); }
             set { SetValue(FontWeightProperty, value); }
         }
-        
+
         /// <summary>
-        /// Gets or sets the font stretch.
+        /// Gets or sets the font stretch used to draw the control's text.
         /// </summary>
         public FontStretch FontStretch
         {
@@ -267,7 +262,7 @@ namespace Avalonia.Controls
         }
 
         /// <summary>
-        /// Gets or sets a brush used to paint the text.
+        /// Gets or sets the brush used to draw the control's text and other foreground elements.
         /// </summary>
         public IBrush? Foreground
         {
@@ -328,127 +323,193 @@ namespace Avalonia.Controls
             get => GetValue(TextDecorationsProperty);
             set => SetValue(TextDecorationsProperty, value);
         }
+        
+        protected override bool BypassFlowDirectionPolicies => true;
 
         /// <summary>
-        /// Gets the value of the attached <see cref="FontFamilyProperty"/> on a control.
+        /// The BaselineOffset property provides an adjustment to baseline offset
         /// </summary>
-        /// <param name="control">The control.</param>
+        public double BaselineOffset
-        /// <returns>The font family.</returns>
-        public static FontFamily GetFontFamily(Control control)
         {
-            return control.GetValue(FontFamilyProperty);
+            get { return (double)GetValue(BaselineOffsetProperty); }
+            set { SetValue(BaselineOffsetProperty, value); }
         }
 
         /// <summary>
-        /// Gets the value of the attached <see cref="FontSizeProperty"/> on a control.
+        /// Reads the attached property from the given element
         /// </summary>
-        /// <param name="control">The control.</param>
+        /// <param name="control">The element to which to read the attached property.</param>
-        /// <returns>The font size.</returns>
+        public static double GetBaselineOffset(Control control)
-        public static double GetFontSize(Control control)
         {
-            return control.GetValue(FontSizeProperty);
+            if (control == null)
+            {
+                throw new ArgumentNullException(nameof(control));
+            }
+
+            return control.GetValue(BaselineOffsetProperty);
         }
 
         /// <summary>
-        /// Gets the value of the attached <see cref="FontStyleProperty"/> on a control.
+        /// Writes the attached property BaselineOffset to the given element.
         /// </summary>
-        /// <param name="control">The control.</param>
+        /// <param name="control">The element to which to write the attached property.</param>
-        /// <returns>The font style.</returns>
+        /// <param name="value">The property value to set</param>
-        public static FontStyle GetFontStyle(Control control)
+        public static void SetBaselineOffset(Control control, double value)
         {
-            return control.GetValue(FontStyleProperty);
+            if (control == null)
+            {
+                throw new ArgumentNullException(nameof(control));
+            }
+
+            control.SetValue(BaselineOffsetProperty, value);
         }
 
         /// <summary>
-        /// Gets the value of the attached <see cref="FontWeightProperty"/> on a control.
+        /// Reads the attached property from the given element
         /// </summary>
-        /// <param name="control">The control.</param>
+        /// <param name="control">The element to which to read the attached property.</param>
-        /// <returns>The font weight.</returns>
+        public static TextAlignment GetTextAlignment(Control control)
-        public static FontWeight GetFontWeight(Control control)
         {
-            return control.GetValue(FontWeightProperty);
+            if (control == null)
+            {
+                throw new ArgumentNullException(nameof(control));
+            }
+
+            return control.GetValue(TextAlignmentProperty);
         }
-        
+
         /// <summary>
-        /// Gets the value of the attached <see cref="FontStretchProperty"/> on a control.
+        /// Writes the attached property BaselineOffset to the given element.
         /// </summary>
-        /// <param name="control">The control.</param>
+        /// <param name="control">The element to which to write the attached property.</param>
-        /// <returns>The font stretch.</returns>
+        /// <param name="alignment">The property value to set</param>
-        public static FontStretch GetFontStretch(Control control)
+        public static void SetTextAlignment(Control control, TextAlignment alignment)
         {
-            return control.GetValue(FontStretchProperty);
+            if (control == null)
+            {
+                throw new ArgumentNullException(nameof(control));
+            }
+
+            control.SetValue(TextAlignmentProperty, alignment);
         }
 
         /// <summary>
-        /// Gets the value of the attached <see cref="ForegroundProperty"/> on a control.
+        /// Reads the attached property from the given element
         /// </summary>
-        /// <param name="control">The control.</param>
+        /// <param name="control">The element to which to read the attached property.</param>
-        /// <returns>The foreground.</returns>
+        public static TextWrapping GetTextWrapping(Control control)
-        public static IBrush? GetForeground(Control control)
         {
-            return control.GetValue(ForegroundProperty);
+            if (control == null)
+            {
+                throw new ArgumentNullException(nameof(control));
+            }
+
+            return control.GetValue(TextWrappingProperty);
         }
 
         /// <summary>
-        /// Sets the value of the attached <see cref="FontFamilyProperty"/> on a control.
+        /// Writes the attached property BaselineOffset to the given element.
         /// </summary>
-        /// <param name="control">The control.</param>
+        /// <param name="control">The element to which to write the attached property.</param>
-        /// <param name="value">The property value to set.</param>
+        /// <param name="wrapping">The property value to set</param>
-        public static void SetFontFamily(Control control, FontFamily value)
+        public static void SetTextWrapping(Control control, TextWrapping wrapping)
         {
-            control.SetValue(FontFamilyProperty, value);
+            if (control == null)
+            {
+                throw new ArgumentNullException(nameof(control));
+            }
+
+            control.SetValue(TextWrappingProperty, wrapping);
         }
 
         /// <summary>
-        /// Sets the value of the attached <see cref="FontSizeProperty"/> on a control.
+        /// Reads the attached property from the given element
         /// </summary>
-        /// <param name="control">The control.</param>
+        /// <param name="control">The element to which to read the attached property.</param>
-        /// <param name="value">The property value to set.</param>
+        public static TextTrimming GetTextTrimming(Control control)
-        public static void SetFontSize(Control control, double value)
         {
-            control.SetValue(FontSizeProperty, value);
+            if (control == null)
+            {
+                throw new ArgumentNullException(nameof(control));
+            }
+
+            return control.GetValue(TextTrimmingProperty);
         }
 
         /// <summary>
-        /// Sets the value of the attached <see cref="FontStyleProperty"/> on a control.
+        /// Writes the attached property BaselineOffset to the given element.
         /// </summary>
-        /// <param name="control">The control.</param>
+        /// <param name="control">The element to which to write the attached property.</param>
-        /// <param name="value">The property value to set.</param>
+        /// <param name="trimming">The property value to set</param>
-        public static void SetFontStyle(Control control, FontStyle value)
+        public static void SetTextTrimming(Control control, TextTrimming trimming)
         {
-            control.SetValue(FontStyleProperty, value);
+            if (control == null)
+            {
+                throw new ArgumentNullException(nameof(control));
+            }
+
+            control.SetValue(TextTrimmingProperty, trimming);
         }
 
         /// <summary>
-        /// Sets the value of the attached <see cref="FontWeightProperty"/> on a control.
+        /// Reads the attached property from the given element
         /// </summary>
-        /// <param name="control">The control.</param>
+        /// <param name="control">The element to which to read the attached property.</param>
-        /// <param name="value">The property value to set.</param>
+        public static double GetLineHeight(Control control)
-        public static void SetFontWeight(Control control, FontWeight value)
         {
-            control.SetValue(FontWeightProperty, value);
+            if (control == null)
+            {
+                throw new ArgumentNullException(nameof(control));
+            }
+
+            return control.GetValue(LineHeightProperty);
         }
-        
+
         /// <summary>
-        /// Sets the value of the attached <see cref="FontStretchProperty"/> on a control.
+        /// Writes the attached property BaselineOffset to the given element.
         /// </summary>
-        /// <param name="control">The control.</param>
+        /// <param name="control">The element to which to write the attached property.</param>
-        /// <param name="value">The property value to set.</param>
+        /// <param name="height">The property value to set</param>
-        public static void SetFontStretch(Control control, FontStretch value)
+        public static void SetLineHeight(Control control, double height)
         {
-            control.SetValue(FontStretchProperty, value);
+            if (control == null)
+            {
+                throw new ArgumentNullException(nameof(control));
+            }
+
+            control.SetValue(LineHeightProperty, height);
         }
 
         /// <summary>
-        /// Sets the value of the attached <see cref="ForegroundProperty"/> on a control.
+        /// Reads the attached property from the given element
         /// </summary>
-        /// <param name="control">The control.</param>
+        /// <param name="control">The element to which to read the attached property.</param>
-        /// <param name="value">The property value to set.</param>
+        public static int GetMaxLines(Control control)
-        public static void SetForeground(Control control, IBrush? value)
         {
-            control.SetValue(ForegroundProperty, value);
+            if (control == null)
+            {
+                throw new ArgumentNullException(nameof(control));
+            }
+
+            return control.GetValue(MaxLinesProperty);
         }
 
+        /// <summary>
+        /// Writes the attached property BaselineOffset to the given element.
+        /// </summary>
+        /// <param name="control">The element to which to write the attached property.</param>
+        /// <param name="maxLines">The property value to set</param>
+        public static void SetMaxLines(Control control, int maxLines)
+        {
+            if (control == null)
+            {
+                throw new ArgumentNullException(nameof(control));
+            }
+
+            control.SetValue(MaxLinesProperty, maxLines);
+        }
+
+
         /// <summary>
         /// Renders the <see cref="TextBlock"/> to a drawing context.
         /// </summary>
@@ -562,7 +623,7 @@ namespace Avalonia.Controls
                 return finalSize;
             }
             
-            _constraint = finalSize;
+            _constraint = new Size(finalSize.Width, Math.Ceiling(finalSize.Height));
             
             _textLayout = null;
 
@@ -588,15 +649,19 @@ namespace Avalonia.Controls
                 case nameof (FontWeight):
                 case nameof (FontStyle):
                 case nameof (FontFamily):
+                case nameof (FontStretch):
 
                 case nameof (TextWrapping):
                 case nameof (TextTrimming):
                 case nameof (TextAlignment):
+
                 case nameof (FlowDirection):
 
                 case nameof (Padding):
                 case nameof (LineHeight):
                 case nameof (MaxLines):
+                    
+                case nameof (InlinesProperty):
 
                 case nameof (Text):
                 case nameof (TextDecorations):

src/Avalonia.Controls/TextBox.cs

@@ -23,6 +23,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// Represents a control that can be used to display or edit unformatted text.
     /// </summary>
+    [TemplatePart("PART_TextPresenter", typeof(TextPresenter))]
     [PseudoClasses(":empty")]
     public class TextBox : TemplatedControl, UndoRedoHelper<TextBox.UndoRedoState>.IUndoRedoHost
     {
@@ -77,6 +78,9 @@ namespace Avalonia.Controls
         public static readonly StyledProperty<int> MaxLengthProperty =
             AvaloniaProperty.Register<TextBox, int>(nameof(MaxLength), defaultValue: 0);
 
+        public static readonly StyledProperty<int> MaxLinesProperty =
+      AvaloniaProperty.Register<TextBox, int>(nameof(MaxLines), defaultValue: 0);
+
         public static readonly DirectProperty<TextBox, string?> TextProperty =
             TextBlock.TextProperty.AddOwnerWithDataValidation<TextBox>(
                 o => o.Text,
@@ -349,6 +353,12 @@ namespace Avalonia.Controls
             set { SetValue(MaxLengthProperty, value); }
         }
 
+        public int MaxLines
+        {
+            get { return GetValue(MaxLinesProperty); }
+            set { SetValue(MaxLinesProperty, value); }
+        }
+
         [Content]
         public string? Text
         {
@@ -670,6 +680,39 @@ namespace Avalonia.Controls
             _selectedTextChangesMadeSinceLastUndoSnapshot++;
             SnapshotUndoRedo(ignoreChangeCount: false);
 
+            if (_presenter != null && MaxLines > 0)
+            {
+                var lineCount = _presenter.TextLayout.TextLines.Count;
+
+                var length = 0;
+
+                var graphemeEnumerator = new GraphemeEnumerator(input.AsMemory());
+
+                while (graphemeEnumerator.MoveNext())
+                {
+                    var grapheme = graphemeEnumerator.Current;
+
+                    if (grapheme.FirstCodepoint.IsBreakChar)
+                    {
+                        if(lineCount + 1 > MaxLines)
+                        {
+                            break;
+                        }
+                        else
+                        {
+                            lineCount++;
+                        }                       
+                    }
+
+                    length += grapheme.Text.Length;
+                }
+
+                if (length < input.Length)
+                {
+                    input = input.Remove(Math.Max(0, length));
+                }
+            }
+
             var text = Text ?? string.Empty;
             var newLength = input.Length + text.Length - Math.Abs(SelectionStart - SelectionEnd);
 
@@ -997,18 +1040,25 @@ namespace Avalonia.Controls
                             SetSelectionForControlBackspace();
                         }
 
-                        if (!DeleteSelection() && caretIndex > 0)
+                        if (!DeleteSelection())
                         {
-                            _presenter.MoveCaretHorizontal(LogicalDirection.Backward);
+                            var characterHit = _presenter.GetNextCharacterHit(LogicalDirection.Backward);
 
-                            var removedCharacters = Math.Max(0, caretIndex - _presenter.CaretIndex);
+                            var backspacePosition = characterHit.FirstCharacterIndex + characterHit.TrailingLength;
-                            
-                            var length = Math.Max(0, caretIndex - removedCharacters);
 
-                            SetTextInternal(text.Substring(0, length) +
+                            if (caretIndex != backspacePosition)
-                                            text.Substring(caretIndex));
+                            {
+                                var start = Math.Min(backspacePosition, caretIndex);
+                                var end = Math.Max(backspacePosition, caretIndex);
 
-                            CaretIndex = _presenter.CaretIndex;
+                                var length = end - start;
+
+                                var editedText = text.Substring(0, start) + text.Substring(Math.Min(end, text.Length));
+
+                                SetTextInternal(editedText);
+
+                                CaretIndex = start;
+                            } 
                         }
                         
                         SnapshotUndoRedo();
@@ -1024,15 +1074,21 @@ namespace Avalonia.Controls
                             SetSelectionForControlDelete();
                         }
 
-                        if (!DeleteSelection() && caretIndex < text.Length)
+                        if (!DeleteSelection())
                         {
                             var characterHit = _presenter.GetNextCharacterHit();
 
-                            var removedCharacters = Math.Max(0,
+                            var nextPosition = characterHit.FirstCharacterIndex + characterHit.TrailingLength;
-                                characterHit.FirstCharacterIndex + characterHit.TrailingLength - caretIndex);
+
+                            if(nextPosition != caretIndex)
+                            {
+                                var start = Math.Min(nextPosition, caretIndex);
+                                var end = Math.Max(nextPosition, caretIndex);
 
-                            SetTextInternal(text.Substring(0, caretIndex) +
+                                var editedText = text.Substring(0, start) + text.Substring(Math.Min(end, text.Length));
-                                            text.Substring(caretIndex + removedCharacters));
+
+                                SetTextInternal(editedText);
+                            }
                         }
 
                         SnapshotUndoRedo();
@@ -1249,17 +1305,17 @@ namespace Avalonia.Controls
 
         private void MoveHorizontal(int direction, bool wholeWord, bool isSelecting)
         {
+            if (_presenter == null)
+            {
+                return;
+            }
+            
             var text = Text ?? string.Empty;
             var selectionStart = SelectionStart;
             var selectionEnd = SelectionEnd;
 
             if (!wholeWord)
             {
-                if (_presenter == null)
-                {
-                    return;
-                }
-                
                 if (isSelecting)
                 {
                     _presenter.MoveCaretToTextPosition(selectionEnd);
@@ -1303,10 +1359,16 @@ namespace Avalonia.Controls
                 
                 SelectionEnd += offset;
 
+                _presenter.MoveCaretToTextPosition(SelectionEnd);
+
                 if (!isSelecting)
                 {
                     CaretIndex = SelectionEnd;
                 }
+                else
+                {
+                    SelectionStart = selectionStart;
+                }
             }
         }
 
@@ -1326,10 +1388,10 @@ namespace Avalonia.Controls
             else
             {
                 var textLines = _presenter.TextLayout.TextLines;
-                var lineIndex = _presenter.TextLayout.GetLineIndexFromCharacterIndex(caretIndex, true);
+                var lineIndex = _presenter.TextLayout.GetLineIndexFromCharacterIndex(caretIndex, false);
                 var textLine = textLines[lineIndex];
 
-                _presenter.MoveCaretToTextPosition(textLine.TextRange.Start);
+                _presenter.MoveCaretToTextPosition(textLine.FirstTextSourceIndex);
             }
         }
 
@@ -1350,16 +1412,10 @@ namespace Avalonia.Controls
             else
             {
                 var textLines = _presenter.TextLayout.TextLines;
-                var lineIndex = _presenter.TextLayout.GetLineIndexFromCharacterIndex(caretIndex, true);
+                var lineIndex = _presenter.TextLayout.GetLineIndexFromCharacterIndex(caretIndex, false);
                 var textLine = textLines[lineIndex];
-                
-                if (caretIndex == textLine.TextRange.Start + textLine.TextRange.Length  - textLine.NewLineLength &&
-                    lineIndex + 1 < textLines.Count)
-                {
-                    textLine = textLines[++lineIndex];
-                }
 
-                var textPosition = textLine.TextRange.Start + textLine.TextRange.Length - textLine.NewLineLength;
+                var textPosition = textLine.FirstTextSourceIndex + textLine.Length;
 
                 _presenter.MoveCaretToTextPosition(textPosition, true);
             }

src/Avalonia.Controls/ToggleSwitch.cs

@@ -9,6 +9,8 @@ namespace Avalonia.Controls
     /// <summary>
     /// A Toggle Switch control.
     /// </summary>
+    [TemplatePart("MovingKnobs", typeof(Panel))]
+    [TemplatePart("SwitchKnob",  typeof(Panel))]
     [PseudoClasses(":dragging")]
     public class ToggleSwitch : ToggleButton
     {

src/Avalonia.Controls/TopLevel.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Reactive.Linq;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Platform;
 using Avalonia.Controls.Primitives;
 using Avalonia.Input;
@@ -14,7 +15,6 @@ using Avalonia.Rendering;
 using Avalonia.Styling;
 using Avalonia.Utilities;
 using Avalonia.VisualTree;
-using JetBrains.Annotations;
 
 namespace Avalonia.Controls
 {
@@ -26,6 +26,7 @@ namespace Avalonia.Controls
     /// It handles scheduling layout, styling and rendering as well as
     /// tracking the widget's <see cref="ClientSize"/>.
     /// </remarks>
+    [TemplatePart("PART_TransparencyFallback", typeof(Border))]
     public abstract class TopLevel : ContentControl,
         IInputRoot,
         ILayoutRoot,
@@ -85,6 +86,8 @@ namespace Avalonia.Controls
         private readonly IKeyboardNavigationHandler? _keyboardNavigationHandler;
         private readonly IPlatformRenderInterface? _renderInterface;
         private readonly IGlobalStyles? _globalStyles;
+        private readonly PointerOverPreProcessor? _pointerOverPreProcessor;
+        private readonly IDisposable? _pointerOverPreProcessorSubscription;
         private Size _clientSize;
         private Size? _frameSize;
         private WindowTransparencyLevel _actualTransparencyLevel;
@@ -193,6 +196,9 @@ namespace Avalonia.Controls
             }
 
             impl.LostFocus += PlatformImpl_LostFocus;
+
+            _pointerOverPreProcessor = new PointerOverPreProcessor(this);
+            _pointerOverPreProcessorSubscription = _inputManager?.PreProcess.Subscribe(_pointerOverPreProcessor);
         }
 
         /// <summary>
@@ -281,9 +287,7 @@ namespace Avalonia.Controls
         /// </summary>
         IKeyboardNavigationHandler IInputRoot.KeyboardNavigationHandler => _keyboardNavigationHandler!;
 
-        /// <summary>
+        /// <inheritdoc/>
-        /// Gets or sets the input element that the pointer is currently over.
-        /// </summary>
         IInputElement? IInputRoot.PointerOverElement
         {
             get { return GetValue(PointerOverElementProperty); }
@@ -348,6 +352,12 @@ namespace Avalonia.Controls
         /// </summary>
         protected virtual ILayoutManager CreateLayoutManager() => new LayoutManager(this);
 
+        public override void InvalidateMirrorTransform()
+        {
+        }
+        
+        protected override bool BypassFlowDirectionPolicies => true;
+        
         /// <summary>
         /// Handles a paint notification from <see cref="ITopLevelImpl.Resized"/>.
         /// </summary>
@@ -370,10 +380,12 @@ namespace Avalonia.Controls
 
             Renderer?.Dispose();
             Renderer = null!;
-            
+
-            (this as IInputRoot).MouseDevice?.TopLevelClosed(this);
+            _pointerOverPreProcessor?.OnCompleted();
+            _pointerOverPreProcessorSubscription?.Dispose();
+
             PlatformImpl = null;
-            
+
             var logicalArgs = new LogicalTreeAttachmentEventArgs(this, this, null);
             ((ILogical)this).NotifyDetachedFromLogicalTree(logicalArgs);
 
@@ -507,12 +519,17 @@ namespace Avalonia.Controls
         /// <param name="e">The event args.</param>
         private void HandleInput(RawInputEventArgs e)
         {
+            if (e is RawPointerEventArgs pointerArgs)
+            {
+                pointerArgs.InputHitTestResult = this.InputHitTest(pointerArgs.Position);
+            }
+
             _inputManager?.ProcessInput(e);
         }
 
         private void SceneInvalidated(object? sender, SceneInvalidatedEventArgs e)
         {
-            (this as IInputRoot).MouseDevice?.SceneInvalidated(this, e.DirtyRect);
+            _pointerOverPreProcessor?.SceneInvalidated(e.DirtyRect);
         }
 
         void PlatformImpl_LostFocus()

src/Avalonia.Controls/TreeView.cs

@@ -849,7 +849,7 @@ namespace Avalonia.Controls
         /// <param name="desired">The desired items.</param>
         private static void SynchronizeItems(IList items, IEnumerable<object> desired)
         {
-            var list = items.Cast<object>().ToList();
+            var list = items.Cast<object>();
             var toRemove = list.Except(desired).ToList();
             var toAdd = desired.Except(list).ToList();
 

src/Avalonia.Controls/TreeViewItem.cs

@@ -12,6 +12,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// An item in a <see cref="TreeView"/>.
     /// </summary>
+    [TemplatePart("PART_Header", typeof(IControl))]
     [PseudoClasses(":pressed", ":selected")]
     public class TreeViewItem : HeaderedItemsControl, ISelectable
     {

src/Avalonia.Controls/Utils/CollectionChangedEventManager.cs

@@ -105,7 +105,7 @@ namespace Avalonia.Controls.Utils
                 static void Notify(
                     INotifyCollectionChanged incc,
                     NotifyCollectionChangedEventArgs args,
-                    List<WeakReference<ICollectionChangedListener>> listeners)
+                    WeakReference<ICollectionChangedListener>[] listeners)
                 {
                     foreach (var l in listeners)
                     {
@@ -132,7 +132,7 @@ namespace Avalonia.Controls.Utils
                     }
                 }
 
-                var l = Listeners.ToList();
+                var l = Listeners.ToArray();
 
                 if (Dispatcher.UIThread.CheckAccess())
                 {

src/Avalonia.Controls/Window.cs

@@ -12,7 +12,6 @@ using Avalonia.Layout;
 using Avalonia.Media;
 using Avalonia.Platform;
 using Avalonia.Styling;
-using JetBrains.Annotations;
 
 namespace Avalonia.Controls
 {
@@ -258,7 +257,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Gets a collection of child windows owned by this window.
         /// </summary>
-        public IReadOnlyList<Window> OwnedWindows => _children.Select(x => x.child).ToList();
+        public IReadOnlyList<Window> OwnedWindows => _children.Select(x => x.child).ToArray();
 
         /// <summary>
         /// Gets or sets a value indicating how the window will size itself to fit its content.
@@ -527,7 +526,7 @@ namespace Avalonia.Controls
 
         private void CloseInternal()
         {
-            foreach (var (child, _) in _children.ToList())
+            foreach (var (child, _) in _children.ToArray())
             {
                 child.CloseInternal();
             }
@@ -551,7 +550,7 @@ namespace Avalonia.Controls
             
             bool canClose = true;
 
-            foreach (var (child, _) in _children.ToList())
+            foreach (var (child, _) in _children.ToArray())
             {
                 if (child.ShouldCancelClose(args))
                 {

src/Avalonia.DesignerSupport/Remote/HtmlTransport/webapp/package-lock.json

@@ -1078,12 +1078,6 @@
             "json5": "^2.1.2"
           }
         },
-        "minimist": {
-          "version": "1.2.5",
-          "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.5.tgz",
-          "integrity": "sha512-FM9nNUYrRBAELZQT3xeZQ7fmMOBg6nWNmJKTcgsJeaLstP/UODVpGsr5OhXhhXg6f+qtJ8uiZ+PUxkDWcgIXLw==",
-          "dev": true
-        },
         "schema-utils": {
           "version": "3.1.1",
           "resolved": "https://registry.npmjs.org/schema-utils/-/schema-utils-3.1.1.tgz",
@@ -1636,9 +1630,9 @@
       }
     },
     "minimist": {
-      "version": "1.2.5",
+      "version": "1.2.6",
-      "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.5.tgz",
+      "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.6.tgz",
-      "integrity": "sha512-FM9nNUYrRBAELZQT3xeZQ7fmMOBg6nWNmJKTcgsJeaLstP/UODVpGsr5OhXhhXg6f+qtJ8uiZ+PUxkDWcgIXLw==",
+      "integrity": "sha512-Jsjnk4bw3YJqYzbdyBiNsPWHPfO++UGG749Cxs6peCu5Xg4nrena6OVxOYxrQTqww0Jmwt+Ref8rggumkTLz9Q==",
       "dev": true
     },
     "mobx": {
@@ -1839,12 +1833,6 @@
             "ms": "^2.1.1"
           }
         },
-        "minimist": {
-          "version": "1.2.5",
-          "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.5.tgz",
-          "integrity": "sha512-FM9nNUYrRBAELZQT3xeZQ7fmMOBg6nWNmJKTcgsJeaLstP/UODVpGsr5OhXhhXg6f+qtJ8uiZ+PUxkDWcgIXLw==",
-          "dev": true
-        },
         "mkdirp": {
           "version": "0.5.5",
           "resolved": "https://registry.npmjs.org/mkdirp/-/mkdirp-0.5.5.tgz",
@@ -2592,12 +2580,6 @@
             "json5": "^2.1.2"
           }
         },
-        "minimist": {
-          "version": "1.2.5",
-          "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.5.tgz",
-          "integrity": "sha512-FM9nNUYrRBAELZQT3xeZQ7fmMOBg6nWNmJKTcgsJeaLstP/UODVpGsr5OhXhhXg6f+qtJ8uiZ+PUxkDWcgIXLw==",
-          "dev": true
-        },
         "schema-utils": {
           "version": "3.1.1",
           "resolved": "https://registry.npmjs.org/schema-utils/-/schema-utils-3.1.1.tgz",

src/Avalonia.Diagnostics/Avalonia.Diagnostics.csproj

@@ -34,4 +34,5 @@
   <Import Project="..\..\build\BuildTargets.targets" />
   <Import Project="..\..\build\ApiDiff.props" />
   <Import Project="..\..\build\NullableEnable.props" />
+  <Import Project="..\..\build\DevAnalyzers.props" />
 </Project>

src/Avalonia.Diagnostics/Diagnostics/ViewModels/ControlDetailsViewModel.cs

@@ -18,7 +18,7 @@ namespace Avalonia.Diagnostics.ViewModels
     internal class ControlDetailsViewModel : ViewModelBase, IDisposable
     {
         private readonly IAvaloniaObject _avaloniaObject;
-        private IDictionary<object, List<PropertyViewModel>>? _propertyIndex;
+        private IDictionary<object, PropertyViewModel[]>? _propertyIndex;
         private PropertyViewModel? _selectedProperty;
         private DataGridCollectionView? _propertiesView;
         private bool _snapshotStyles;
@@ -472,9 +472,9 @@ namespace Avalonia.Diagnostics.ViewModels
                 .Concat(GetClrProperties(o, _showImplementedInterfaces))
                 .OrderBy(x => x, PropertyComparer.Instance)
                 .ThenBy(x => x.Name)
-                .ToList();
+                .ToArray();
 
-            _propertyIndex = properties.GroupBy(x => x.Key).ToDictionary(x => x.Key, x => x.ToList());
+            _propertyIndex = properties.GroupBy(x => x.Key).ToDictionary(x => x.Key, x => x.ToArray());
 
             var view = new DataGridCollectionView(properties);
             view.GroupDescriptions.Add(new DataGridPathGroupDescription(nameof(AvaloniaPropertyViewModel.Group)));

src/Avalonia.Diagnostics/Diagnostics/ViewModels/MainViewModel.cs

@@ -7,7 +7,6 @@ using Avalonia.Diagnostics.Models;
 using Avalonia.Input;
 using Avalonia.Metadata;
 using Avalonia.Threading;
-using System.Reactive.Linq;
 using System.Linq;
 
 namespace Avalonia.Diagnostics.ViewModels
@@ -59,8 +58,8 @@ namespace Avalonia.Diagnostics.ViewModels
                     .Subscribe(e =>
                         {
                             PointerOverRoot = e.Root;
-                            PointerOverElement = e.Root.GetInputElementsAt(e.Position).FirstOrDefault();
+                            PointerOverElement = e.Root.InputHitTest(e.Position);
-                        });                                     
+                        });
 #nullable restore
             }
             Console = new ConsoleViewModel(UpdateConsoleContext);

src/Avalonia.Diagnostics/Diagnostics/Views/ConsoleView.xaml

@@ -11,7 +11,7 @@
                   BorderBrush="{TemplateBinding BorderBrush}"
                   BorderThickness="{TemplateBinding BorderThickness}">
             <DockPanel Margin="{TemplateBinding Padding}">
-              <TextBlock DockPanel.Dock="Left" Margin="0,0,4,0">></TextBlock>
+              <TextBlock DockPanel.Dock="Left" Margin="0,0,4,0"></TextBlock>
               <TextPresenter Name="PART_TextPresenter"
                              Text="{TemplateBinding Text, Mode=TwoWay}"
                              CaretIndex="{TemplateBinding CaretIndex}"
@@ -44,7 +44,7 @@
         <DataTemplate>
           <StackPanel Orientation="Vertical">
             <DockPanel>
-              <TextBlock DockPanel.Dock="Left" Margin="0,0,4,0">></TextBlock>
+              <TextBlock DockPanel.Dock="Left" Margin="0,0,4,0"></TextBlock>
               <TextBlock Text="{Binding Input}"/>
             </DockPanel>
             <TextBlock Foreground="{Binding Foreground}" Text="{Binding Output}"/>