Merge branch 'master' into feature/add_handling_input_message_previewer

Avalonia.sln.DotSettings

@@ -37,4 +37,5 @@
 	<s:String x:Key="/Default/CodeStyle/Naming/CSharpNaming/PredefinedNamingRules/=StaticReadonly/@EntryIndexedValue">&lt;Policy Inspect="True" Prefix="" Suffix="" Style="AaBb" /&gt;</s:String>
 	<s:String x:Key="/Default/CodeStyle/Naming/CSharpNaming/PredefinedNamingRules/=TypeParameters/@EntryIndexedValue">&lt;Policy Inspect="False" Prefix="T" Suffix="" Style="AaBb" /&gt;</s:String>
 	<s:String x:Key="/Default/CodeStyle/Naming/CSharpNaming/PredefinedNamingRules/=TypesAndNamespaces/@EntryIndexedValue">&lt;Policy Inspect="False" Prefix="" Suffix="" Style="AaBb" /&gt;</s:String>
+	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EFeature_002EServices_002EDaemon_002ESettings_002EMigration_002ESwaWarningsModeSettingsMigrate/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=Avalonia/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>

azure-pipelines.yml

@@ -31,6 +31,8 @@ jobs:
     condition: not(canceled())
      
 - job: macOS
+  variables:
+    SolutionDir: '$(Build.SourcesDirectory)'
   pool:
     vmImage: 'macOS-10.14'
   steps:
@@ -97,6 +99,8 @@ jobs:
 - job: Windows
   pool:
     vmImage: 'windows-2019'
+  variables:
+    SolutionDir: '$(Build.SourcesDirectory)'
   steps:
   - task: UseDotNet@2
     displayName: 'Use .NET Core SDK 3.1.401'

build.ps1

@@ -62,6 +62,8 @@ else {
     } else {
         ExecSafe { & $DotNetInstallFile -InstallDir $DotNetDirectory -Version $DotNetVersion -NoPath }
     }
+
+    $env:PATH="$DotNetDirectory;$env:PATH"
 }
 
 Write-Output "Microsoft (R) .NET Core SDK version $(& $env:DOTNET_EXE --version)"

build/ApiDiff.props

@@ -7,6 +7,6 @@
     <ItemGroup>
       <PackageDownload Include="$(NugetPackageName)" Version="[$(ApiContractPackageVersion)]" />
       <PackageReference Include="Microsoft.DotNet.ApiCompat" Version="5.0.0-beta.20372.2" PrivateAssets="All" />
-    <ResolvedMatchingContract Include="$(NuGetPackageRoot)\$(NugetPackageName.ToLower())\$(ApiContractPackageVersion)\lib\$(TargetFramework)\$(AssemblyName).dll" />
+      <ResolvedMatchingContract Include="$(NuGetPackageRoot)\$(NugetPackageName.ToLowerInvariant())\$(ApiContractPackageVersion)\lib\$(TargetFramework)\$(AssemblyName).dll" />
     </ItemGroup>
 </Project>

build/SharedVersion.props

@@ -10,10 +10,17 @@
     <NoWarn>CS1591</NoWarn>
     <LangVersion>latest</LangVersion>
     <PackageLicenseExpression>MIT</PackageLicenseExpression>
-    <PackageIconUrl>https://avatars2.githubusercontent.com/u/14075148?s=200</PackageIconUrl>
+    <PackageIcon>Icon.png</PackageIcon>
     <PackageDescription>Avalonia is a WPF/UWP-inspired cross-platform XAML-based UI framework providing a flexible styling system and supporting a wide range of Operating Systems such as Windows (.NET Framework, .NET Core), Linux (via Xorg), MacOS and with experimental support for Android and iOS.</PackageDescription>
     <PackageTags>avalonia;avaloniaui;mvvm;rx;reactive extensions;android;ios;mac;forms;wpf;net;netstandard;net461;uwp;xamarin</PackageTags>
     <PackageReleaseNotes>https://github.com/AvaloniaUI/Avalonia/releases</PackageReleaseNotes>
     <RepositoryType>git</RepositoryType>
+    <AssemblyOriginatorKeyFile>$(MSBuildThisFileDirectory)\avalonia.snk</AssemblyOriginatorKeyFile>
+    <SignAssembly>false</SignAssembly>
+    <DefineConstants Condition="$(SignAssembly) == true">$(DefineConstants);SIGNED_BUILD</DefineConstants>
   </PropertyGroup>
+
+  <ItemGroup Label="PackageIcon">
+    <None Include="$(MSBuildThisFileDirectory)/Assets/Icon.png" Pack="true" PackagePath=""/>
+  </ItemGroup>
 </Project>

build/SourceLink.props

@@ -1,5 +1,5 @@
 <Project>
   <ItemGroup>
-    <PackageReference Include="SourceLink.Create.CommandLine" Version="2.8.0" PrivateAssets="All" />
+    <PackageReference Include="SourceLink.Create.CommandLine" Version="2.8.3" PrivateAssets="All" />
   </ItemGroup>
-</Project>
+</Project>

build/XUnit.props

@@ -11,4 +11,8 @@
     <PackageReference Include="Xunit.SkippableFact" Version="1.3.6" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.7.0" />
   </ItemGroup>
+  <PropertyGroup>
+    <AssemblyOriginatorKeyFile>$(MSBuildThisFileDirectory)\avalonia.snk</AssemblyOriginatorKeyFile>
+    <SignAssembly>False</SignAssembly>
+  </PropertyGroup>
 </Project>

dirs.proj

@@ -21,6 +21,7 @@
   <ItemGroup Condition="!$([MSBuild]::IsOsPlatform('Windows')) OR '$(MSBuildRuntimeType)' != 'Full'">
     <ProjectReference Remove="src/Windows/Avalonia.Win32.Interop/Avalonia.Win32.Interop.csproj" />
     <ProjectReference Remove="samples/interop/**/*.*proj" />
+    <ProjectReference Remove="samples/ControlCatalog.Desktop/*.*proj" />
   </ItemGroup>
 
   <ItemGroup>

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

@@ -1338,6 +1338,12 @@ NSArray* AllLoopModes = [NSArray arrayWithObjects: NSDefaultRunLoopMode, NSEvent
     }
     
     _parent->BaseEvents->RunRenderPriorityJobs();
+    
+    if (_parent == nullptr)
+    {
+        return;
+    }
+        
     _parent->BaseEvents->Paint();
 }
 

nukebuild/Build.cs

@@ -138,9 +138,19 @@ partial class Build : NukeBuild
                 .SetWorkingDirectory(webappDir)
                 .SetCommand("dist"));
         });
-    
+
-    Target Compile => _ => _
+    Target CompileNative => _ => _
         .DependsOn(Clean)
+        .OnlyWhenStatic(() => EnvironmentInfo.IsOsx)
+        .Executes(() =>
+        {
+            var project = $"{RootDirectory}/native/Avalonia.Native/src/OSX/Avalonia.Native.OSX.xcodeproj/";
+            var args = $"-project {project} -configuration {Parameters.Configuration} CONFIGURATION_BUILD_DIR={RootDirectory}/Build/Products/Release";
+            ProcessTasks.StartProcess("xcodebuild", args).AssertZeroExitCode();
+        });
+
+    Target Compile => _ => _
+        .DependsOn(Clean, CompileNative)
         .DependsOn(CompileHtmlPreviewer)
         .Executes(async () =>
         {

nukebuild/BuildTasksPatcher.cs

@@ -29,7 +29,11 @@ public class BuildTasksPatcher
                             InputAssemblies = new[]
                             {
                                 temp, typeof(Mono.Cecil.AssemblyDefinition).Assembly.GetModules()[0]
-                                    .FullyQualifiedName
+                                    .FullyQualifiedName,
+                                typeof(Mono.Cecil.Rocks.MethodBodyRocks).Assembly.GetModules()[0].FullyQualifiedName,
+                                typeof(Mono.Cecil.Pdb.PdbReaderProvider).Assembly.GetModules()[0].FullyQualifiedName,
+                                typeof(Mono.Cecil.Mdb.MdbReaderProvider).Assembly.GetModules()[0].FullyQualifiedName
+                                
                             },
                             SearchDirectories = new string[0],
                             OutputFile = output

nukebuild/_build.csproj

@@ -16,7 +16,7 @@
     <PackageReference Include="vswhere" Version="2.6.7" Condition=" '$(OS)' == 'Windows_NT' " />
     <PackageReference Include="ILRepack.NETStandard" Version="2.0.4" />
     <!-- Keep in sync with Avalonia.Build.Tasks -->
-    <PackageReference Include="Avalonia.Unofficial.Cecil" Version="20190417.2.0" />
+    <PackageReference Include="Mono.Cecil" Version="0.11.2" />
     <PackageReference Include="Pharmacist.Core" Version="1.8.1" />
   </ItemGroup>
 

packages/Avalonia/AvaloniaBuildTasks.targets

@@ -87,6 +87,9 @@
       ProjectDirectory="$(MSBuildProjectDirectory)"
       VerifyIl="$(AvaloniaXamlIlVerifyIl)"
       ReportImportance="$(AvaloniaXamlReportImportance)"
+      AssemblyOriginatorKeyFile="$(AssemblyOriginatorKeyFile)"
+      SignAssembly="$(SignAssembly)"
+      DelaySign="$(DelaySign)"
     />
     <Exec
       Condition="'$(_AvaloniaUseExternalMSBuild)' == 'true'"

readme.md

@@ -39,7 +39,7 @@ Examples of UIs built with Avalonia
 
 ## JetBrains Rider
 
-If you need to develop Avalonia app with JetBrains Rider, go and *vote* on [this issue](https://youtrack.jetbrains.com/issue/RIDER-39247) in their tracker. JetBrains won't do things without their users telling them that they want the feature, so only **YOU** can make it happen.
+If you need to develop Avalonia app with JetBrains Rider you can use latest Rider [preview builds](https://www.jetbrains.com/rider/nextversion/).
 
 ## Bleeding Edge Builds
 

samples/BindingDemo/App.xaml.cs

@@ -1,6 +1,5 @@
-using System;
 using Avalonia;
-using Avalonia.Controls;
+using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Markup.Xaml;
 using Avalonia.ReactiveUI;
 
@@ -13,13 +12,20 @@ namespace BindingDemo
             AvaloniaXamlLoader.Load(this);
         }
 
-        private static void Main()
+        public override void OnFrameworkInitializationCompleted()
         {
-            AppBuilder.Configure<App>()
+            if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
+                desktop.MainWindow = new MainWindow();
+            base.OnFrameworkInitializationCompleted();
+        }
+
+        public static int Main(string[] args)
+            => BuildAvaloniaApp().StartWithClassicDesktopLifetime(args);
+
+        public static AppBuilder BuildAvaloniaApp()
+          => AppBuilder.Configure<App>()
                 .UsePlatformDetect()
                 .UseReactiveUI()
-                .LogToDebug()
+                .LogToTrace();
-                .Start<MainWindow>();
-        }
     }
 }

samples/ControlCatalog.Desktop/ControlCatalog.Desktop.csproj

@@ -3,6 +3,7 @@
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <TargetFramework>net461</TargetFramework>
+    <PlatformTarget>x64</PlatformTarget>
   </PropertyGroup>
 
   <ItemGroup>

samples/ControlCatalog.Desktop/Program.cs

@@ -10,19 +10,15 @@ namespace ControlCatalog
     internal class Program
     {
         [STAThread]
-        static void Main(string[] args)
+        public static int Main(string[] args)
-        {
+            => BuildAvaloniaApp().StartWithClassicDesktopLifetime(args);
-            // TODO: Make this work with GTK/Skia/Cairo depending on command-line args
-            // again.
-            BuildAvaloniaApp().Start<MainWindow>();
-        }
 
         /// <summary>
         /// This method is needed for IDE previewer infrastructure
         /// </summary>
         public static AppBuilder BuildAvaloniaApp()
             => AppBuilder.Configure<App>()
-                .LogToDebug()
+                .LogToTrace()
                 .UsePlatformDetect()
                 .UseReactiveUI();
 

samples/ControlCatalog.NetCore/ControlCatalog.NetCore.csproj

@@ -11,9 +11,8 @@
     <ProjectReference Include="..\..\src\Avalonia.Dialogs\Avalonia.Dialogs.csproj" />
     <ProjectReference Include="..\..\src\Linux\Avalonia.LinuxFramebuffer\Avalonia.LinuxFramebuffer.csproj" />
     <ProjectReference Include="..\ControlCatalog\ControlCatalog.csproj" />
-    <ProjectReference Include="..\..\src\Avalonia.Desktop\Avalonia.Desktop.csproj" />
     <ProjectReference Include="..\..\src\Avalonia.X11\Avalonia.X11.csproj" />
-    <PackageReference Include="Avalonia.Angle.Windows.Natives" Version="2.1.0.2019013001" />
+    <PackageReference Include="Avalonia.Angle.Windows.Natives" Version="2.1.0.2020091801" />
   </ItemGroup>
 
 

samples/ControlCatalog.NetCore/Program.cs

@@ -7,12 +7,11 @@ using System.Threading.Tasks;
 using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Controls.ApplicationLifetimes;
+using Avalonia.Dialogs;
 using Avalonia.Headless;
 using Avalonia.LogicalTree;
-using Avalonia.Skia;
 using Avalonia.ReactiveUI;
 using Avalonia.Threading;
-using Avalonia.Dialogs;
 
 namespace ControlCatalog.NetCore
 {
@@ -121,7 +120,7 @@ namespace ControlCatalog.NetCore
                 .UseSkia()
                 .UseReactiveUI()
                 .UseManagedSystemDialogs()
-                .LogToDebug();
+                .LogToTrace();
 
         static void SilenceConsole()
         {

samples/ControlCatalog/App.xaml

@@ -12,6 +12,16 @@
     <Style Selector="TextBlock.h3">
       <Setter Property="FontSize" Value="12" />
     </Style>
+    <Style Selector="Label.h1">
+      <Setter Property="FontSize" Value="16" />
+      <Setter Property="FontWeight" Value="Medium" />
+    </Style>
+    <Style Selector="Label.h2">
+      <Setter Property="FontSize" Value="14" />
+    </Style>
+    <Style Selector="Label.h3">
+      <Setter Property="FontSize" Value="12" />
+    </Style>
     <StyleInclude Source="/SideBar.xaml"/>
   </Application.Styles>
 </Application>

samples/ControlCatalog/App.xaml.cs

@@ -81,7 +81,7 @@ namespace ControlCatalog
 
         public override void Initialize()
         {
-            Styles.Insert(0, FluentDark);
+            Styles.Insert(0, FluentLight);
 
             AvaloniaXamlLoader.Load(this);
         }

samples/ControlCatalog/MainView.xaml

@@ -44,6 +44,7 @@
                ScrollViewer.HorizontalScrollBarVisibility="Disabled">
         <pages:ItemsRepeaterPage/>
       </TabItem>
+      <TabItem Header="Label"><pages:LabelsPage/></TabItem>
       <TabItem Header="LayoutTransformControl"><pages:LayoutTransformControlPage/></TabItem>
       <TabItem Header="ListBox"
                ScrollViewer.VerticalScrollBarVisibility="Disabled">
@@ -77,8 +78,8 @@
             <ComboBoxItem>Full Decorations</ComboBoxItem>
           </ComboBox>
           <ComboBox x:Name="Themes" SelectedIndex="0">
-            <ComboBoxItem>Fluent - Dark</ComboBoxItem>
             <ComboBoxItem>Fluent - Light</ComboBoxItem>
+            <ComboBoxItem>Fluent - Dark</ComboBoxItem>
             <ComboBoxItem>Simple - Light</ComboBoxItem>
             <ComboBoxItem>Simple - Dark</ComboBoxItem>
           </ComboBox>

samples/ControlCatalog/MainView.xaml.cs

@@ -38,10 +38,10 @@ namespace ControlCatalog
                 switch (themes.SelectedIndex)
                 {
                     case 0:
-                        Application.Current.Styles[0] = App.FluentDark;
+                        Application.Current.Styles[0] = App.FluentLight;
                         break;
                     case 1:
-                        Application.Current.Styles[0] = App.FluentLight;
+                        Application.Current.Styles[0] = App.FluentDark;
                         break;
                     case 2:
                         Application.Current.Styles[0] = App.DefaultLight;

samples/ControlCatalog/Pages/AutoCompleteBoxPage.xaml

@@ -1,5 +1,6 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:sys="clr-namespace:System;assembly=netstandard"
              x:Class="ControlCatalog.Pages.AutoCompleteBoxPage">
   <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">AutoCompleteBox</TextBlock>
@@ -51,6 +52,21 @@
                          Width="200"
                          Margin="0,0,0,8"
                          FilterMode="None"/>
+        <TextBlock Text="Custom Autocomplete"/>
+        <AutoCompleteBox Name="CustomAutocompleteBox"
+                         Width="200"
+                         Margin="0,0,0,8"
+                         FilterMode="None"/>
+        
+        <TextBlock Text="With Validation Errors"/>
+        <AutoCompleteBox Name="ValidationErrors"
+                         Width="200"
+                         Margin="0,0,0,8"
+                         FilterMode="None">
+          <DataValidationErrors.Error>
+            <sys:Exception /> 
+          </DataValidationErrors.Error>
+        </AutoCompleteBox>
       </StackPanel>
     </StackPanel>
   </StackPanel>

samples/ControlCatalog/Pages/AutoCompleteBoxPage.xaml.cs

@@ -92,13 +92,28 @@ namespace ControlCatalog.Pages
         }
         public StateData[] States { get; private set; }
         
+        private LinkedList<string>[] BuildAllSentences()
+        {
+            return new string[]
+            {
+                "Hello world",
+                "No this is Patrick",
+                "Never gonna give you up",
+                "How does one patch KDE2 under FreeBSD"
+            }
+            .Select(x => new LinkedList<string>(x.Split(' ')))
+            .ToArray();
+        }
+        public LinkedList<string>[] Sentences { get; private set; }
+
         public AutoCompleteBoxPage()
         {
             this.InitializeComponent();
 
             States = BuildAllStates();
+            Sentences = BuildAllSentences();
 
-            foreach (AutoCompleteBox box in GetAllAutoCompleteBox())
+            foreach (AutoCompleteBox box in GetAllAutoCompleteBox().Where(x => x.Name != "CustomAutocompleteBox"))
             {
                 box.Items = States;
             }
@@ -116,6 +131,11 @@ namespace ControlCatalog.Pages
 
             var asyncBox = this.FindControl<AutoCompleteBox>("AsyncBox");
             asyncBox.AsyncPopulator = PopulateAsync;
+
+            var customAutocompleteBox = this.FindControl<AutoCompleteBox>("CustomAutocompleteBox");
+            customAutocompleteBox.Items = Sentences.SelectMany(x => x);
+            customAutocompleteBox.TextFilter = LastWordContains;
+            customAutocompleteBox.TextSelector = AppendWord;
         }
         private IEnumerable<AutoCompleteBox> GetAllAutoCompleteBox()
         {
@@ -137,6 +157,42 @@ namespace ControlCatalog.Pages
                       .ToList();
         }
 
+        private bool LastWordContains(string searchText, string item)
+        {
+            var words = searchText.Split(' ');
+            var options = Sentences.Select(x => x.First).ToArray();
+            for (var i = 0; i < words.Length; ++i)
+            {
+                var word = words[i];
+                for (var j = 0; j < options.Length; ++j)
+                {
+                    var option = options[j];
+                    if (option == null)
+                        continue;
+
+                    if (i == words.Length - 1)
+                    {
+                        options[j] = option.Value.ToLower().Contains(word.ToLower()) ? option : null;
+                    }
+                    else
+                    {
+                        options[j] = option.Value.Equals(word, StringComparison.InvariantCultureIgnoreCase) ? option.Next : null;
+                    }
+                }
+            }
+
+            return options.Any(x => x != null && x.Value == item);
+        }
+        private string AppendWord(string text, string item)
+        {
+            string[] parts = text.Split(' ');
+            if (parts.Length == 0)
+                return item;
+
+            parts[parts.Length - 1] = item;
+            return string.Join(" ", parts);
+        }
+
         private void InitializeComponent()
         {
             AvaloniaXamlLoader.Load(this);

samples/ControlCatalog/Pages/ButtonSpinnerPage.xaml

@@ -1,6 +1,7 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             x:Class="ControlCatalog.Pages.ButtonSpinnerPage">
+             x:Class="ControlCatalog.Pages.ButtonSpinnerPage"
+             xmlns:sys="clr-namespace:System;assembly=netstandard">
 
   <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">ButtonSpinner</TextBlock>
@@ -19,6 +20,14 @@
                      ShowButtonSpinner="{Binding #showSpinCheck.IsChecked}">
         <TextBlock HorizontalAlignment="Center" VerticalAlignment="Center" Text="Everest"/>
       </ButtonSpinner>
+      <ButtonSpinner MinHeight="30" Spin="OnSpin" ButtonSpinnerLocation="Left"
+                     AllowSpin="{Binding #allowSpinCheck.IsChecked}"
+                     ShowButtonSpinner="{Binding #showSpinCheck.IsChecked}">
+        <DataValidationErrors.Error>
+          <sys:Exception /> 
+        </DataValidationErrors.Error>
+        <TextBlock HorizontalAlignment="Center" VerticalAlignment="Center" Text="Everest"/>
+      </ButtonSpinner>
     </StackPanel>
   </StackPanel>
 

samples/ControlCatalog/Pages/ComboBoxPage.xaml

@@ -1,6 +1,7 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             x:Class="ControlCatalog.Pages.ComboBoxPage">
+             x:Class="ControlCatalog.Pages.ComboBoxPage"
+             xmlns:sys="clr-namespace:System;assembly=netstandard">
   <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">ComboBox</TextBlock>
     <TextBlock Classes="h2">A drop-down list.</TextBlock>
@@ -35,6 +36,16 @@
            </DataTemplate>
          </ComboBox.ItemTemplate>
        </ComboBox>
+      
+      <ComboBox PlaceholderText="Pick an Item">
+        <ComboBoxItem>Inline Items</ComboBoxItem>
+        <ComboBoxItem>Inline Item 2</ComboBoxItem>
+        <ComboBoxItem>Inline Item 3</ComboBoxItem>
+        <ComboBoxItem>Inline Item 4</ComboBoxItem>
+        <DataValidationErrors.Error>
+          <sys:Exception /> 
+        </DataValidationErrors.Error>
+      </ComboBox>
     </StackPanel>
 
   </StackPanel>

samples/ControlCatalog/Pages/DataGridPage.xaml

@@ -11,12 +11,17 @@
       <Setter Property="Background" Value="{Binding Path=GDP, Mode=OneWay, Converter={StaticResource GDPConverter}}" />
     </Style>
   </UserControl.Styles>
-  <Grid RowDefinitions="Auto,*">
+  <Grid RowDefinitions="Auto,Auto,*">
     <StackPanel Orientation="Vertical" Spacing="4" Grid.Row="0">
       <TextBlock Classes="h1">DataGrid</TextBlock>
       <TextBlock Classes="h2">A control for displaying and interacting with a data source.</TextBlock>
     </StackPanel>
-    <TabControl Grid.Row="1">
+    <StackPanel Grid.Row="1" Spacing="4" Orientation="Horizontal" IsVisible="{Binding #EditableTab.IsSelected}">
+      <TextBlock Text="FontSize:" VerticalAlignment="Center"/>
+      <Slider x:Name="FontSizeSlider" Minimum="5" Maximum="30" Value="14" Width="100" VerticalAlignment="Center" />
+      <CheckBox x:Name="IsThreeStateCheckBox" IsChecked="False" Content="IsThreeState"/>
+    </StackPanel>
+    <TabControl Grid.Row="2">
       <TabItem Header="DataGrid">
         <DataGrid Name="dataGrid1" Margin="12" CanUserResizeColumns="True" CanUserReorderColumns="True" CanUserSortColumns="True" HeadersVisibility="All">
           <DataGrid.Columns>
@@ -39,13 +44,13 @@
           </DataGrid.Columns>
         </DataGrid>
       </TabItem>
-      <TabItem Header="Editable">
+      <TabItem x:Name="EditableTab" Header="Editable">
         <Grid RowDefinitions="*,Auto">
           <DataGrid Name="dataGridEdit" Margin="12" Grid.Row="0">
             <DataGrid.Columns>
-              <DataGridTextColumn Header="First Name" Binding="{Binding FirstName}" Width="2*" />
+              <DataGridTextColumn Header="First Name" Binding="{Binding FirstName}" Width="2*" FontSize="{Binding #FontSizeSlider.Value, Mode=OneWay}" />
-              <DataGridTextColumn Header="Last" Binding="{Binding LastName}" Width="2*" />
+              <DataGridTextColumn Header="Last" Binding="{Binding LastName}" Width="2*" FontSize="{Binding #FontSizeSlider.Value, Mode=OneWay}" />
-              <DataGridCheckBoxColumn Header="Is Banned" Binding="{Binding IsBanned}" Width="*" />
+              <DataGridCheckBoxColumn Header="Is Banned" Binding="{Binding IsBanned}" Width="*" IsThreeState="{Binding #IsThreeStateCheckBox.IsChecked, Mode=OneWay}" />
             </DataGrid.Columns>
           </DataGrid>
           <Button Grid.Row="1" Name="btnAdd" Margin="12,0,12,12" Content="Add" HorizontalAlignment="Right" />

samples/ControlCatalog/Pages/DateTimePickerPage.xaml

@@ -2,6 +2,7 @@
              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"
+             xmlns:sys="clr-namespace:System;assembly=netstandard"
              mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
              x:Class="ControlCatalog.Pages.DateTimePickerPage">
   <StackPanel Orientation="Vertical" Spacing="4" HorizontalAlignment="Stretch">
@@ -30,6 +31,16 @@
         </Panel>
       </StackPanel>
       
+      
+      <Border BorderBrush="{DynamicResource SystemControlHighlightBaseLowBrush}"
+              BorderThickness="1" Padding="15">
+        <DatePicker Header="Pick a date">
+          <DataValidationErrors.Error>
+            <sys:Exception /> 
+          </DataValidationErrors.Error>
+        </DatePicker>
+      </Border>
+      
       <TextBlock FontSize="18">A DatePicker with day formatted and year hidden.</TextBlock>
       <StackPanel Orientation="Vertical">
         <Border BorderBrush="{DynamicResource SystemControlHighlightBaseLowBrush}"
@@ -66,6 +77,15 @@
           </TextBlock>
         </Panel>
       </StackPanel>
+      
+      <Border BorderBrush="{DynamicResource SystemControlHighlightBaseLowBrush}"
+              BorderThickness="1" Padding="15">
+        <TimePicker Header="Pick a time">
+          <DataValidationErrors.Error>
+            <sys:Exception /> 
+          </DataValidationErrors.Error>
+        </TimePicker>
+      </Border>
 
       <TextBlock FontSize="18">A TimePicker with a header and minute increments specified.</TextBlock>
       <StackPanel Orientation="Vertical">

samples/ControlCatalog/Pages/LabelsPage.axaml

@@ -0,0 +1,42 @@
+<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="400" d:DesignHeight="250"
+             x:Class="ControlCatalog.Pages.LabelsPage"
+             x:Name="_labelsPage">
+    <UserControl.Styles>
+        <Style Selector="Label">
+            <Setter Property="VerticalAlignment" Value="Center"/>
+            <Setter Property="Margin" Value="6,3,0,3"/>
+        </Style>
+        <Style Selector="TextBox">
+            <Setter Property="VerticalAlignment" Value="Center"/>
+            <Setter Property="Margin" Value="0,3,6,3"/>
+        </Style>
+        <Style Selector="CheckBox">
+            <Setter Property="VerticalAlignment" Value="Center"/>
+            <Setter Property="Margin" Value="0,3,6,3"/>
+        </Style>
+        <Style Selector="Button[IsDefault=true]">
+            <Setter Property="Background" Value="{DynamicResource HighlightBrush}"/>
+        </Style>
+    </UserControl.Styles>
+    <ScrollViewer VerticalScrollBarVisibility="Auto" 
+                  HorizontalScrollBarVisibility="Hidden">
+        <Grid HorizontalAlignment="Left" VerticalAlignment="Top" RowDefinitions="Auto,Auto,Auto,Auto,Auto,*" ColumnDefinitions="Auto,6,*" Width="246">
+            <Label Target="firstNameEdit" Grid.Row="0" Grid.Column="0">_First name</Label>
+            <TextBox Name="firstNameEdit" Grid.Column="2" Grid.Row="0" Text="{Binding FirstName}"></TextBox>
+            <Label Target="lastNameEdit" Grid.Row="1" Grid.Column="0">_Last name</Label>
+            <TextBox Name="lastNameEdit" Grid.Column="2" Grid.Row="1" Text="{Binding LastName}"></TextBox>
+            <Label Target="bannedCheck" Grid.Row="2" Grid.Column="0">_Banned</Label>
+            <CheckBox Name="bannedCheck" Grid.Column="2" Grid.Row="2" IsChecked="{Binding IsBanned}"></CheckBox>
+            <GridSplitter Grid.Column="1" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" Grid.RowSpan="3" >
+            </GridSplitter>
+            <StackPanel Grid.Column="0" Grid.Row="4" Grid.ColumnSpan="3" Orientation="Horizontal" HorizontalAlignment="Right">
+                <Button IsCancel="True" Command="{Binding #_labelsPage.DoCancel}">Cancel</Button>
+                <Button IsDefault="True" Command="{Binding #_labelsPage.DoSave}">Save</Button>
+            </StackPanel>
+        </Grid>
+    </ScrollViewer>
+</UserControl>

samples/ControlCatalog/Pages/LabelsPage.axaml.cs

@@ -0,0 +1,43 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+using ControlCatalog.Models;
+using ReactiveUI;
+
+namespace ControlCatalog.Pages
+{
+    public class LabelsPage : UserControl
+    {
+        private Person _person;
+
+        public LabelsPage()
+        {
+            CreateDefaultPerson();
+            this.InitializeComponent();
+        }
+
+        private void CreateDefaultPerson()
+        {
+            DataContext = _person = new Person
+            {
+                FirstName = "John",
+                LastName = "Doe",
+                IsBanned = true,
+            };
+        }
+
+        private void InitializeComponent()
+        {
+            AvaloniaXamlLoader.Load(this);
+        }
+
+        public void DoSave()
+        {
+            
+        }
+        public void DoCancel()
+        {
+            CreateDefaultPerson();
+        }
+    }
+}

samples/ControlCatalog/Pages/NumericUpDownPage.xaml

@@ -1,5 +1,6 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:sys="clr-namespace:System;assembly=netstandard"
              x:Class="ControlCatalog.Pages.NumericUpDownPage">
   <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Margin="2" Classes="h1">Numeric up-down control</TextBlock>
@@ -75,6 +76,15 @@
       <NumericUpDown Name="upDown" Minimum="0" Maximum="10" Increment="0.5"
                      CultureInfo="en-US" VerticalAlignment="Center"
                      Watermark="Enter text" FormatString="{Binding SelectedFormat.Value}"/>
+      
+      <TextBlock FontSize="14" FontWeight="Bold" VerticalAlignment="Center">NumericUpDown with Validation Errors:</TextBlock>
+      <NumericUpDown Minimum="0" Maximum="10" Increment="0.5"
+                     CultureInfo="en-US" VerticalAlignment="Center"
+                     Watermark="Enter text" FormatString="{Binding SelectedFormat.Value}">
+        <DataValidationErrors.Error>
+          <sys:Exception /> 
+        </DataValidationErrors.Error>
+      </NumericUpDown>
     </StackPanel>
 
   </StackPanel>

samples/ControlCatalog/Pages/OpenGlPage.xaml.cs

@@ -7,6 +7,7 @@ using System.Runtime.InteropServices;
 using Avalonia;
 using Avalonia.Controls;
 using Avalonia.OpenGL;
+using Avalonia.OpenGL.Controls;
 using Avalonia.Platform.Interop;
 using Avalonia.Threading;
 using static Avalonia.OpenGL.GlConsts;

samples/ControlCatalog/Pages/RelativePanelPage.axaml

@@ -23,16 +23,16 @@
         <Border Name="Rect6" Background="Green" Height="50" Width="50" RelativePanel.AlignBottomWithPanel="True" RelativePanel.AlignRightWithPanel="True">
             <TextBlock Text="Rect6" Foreground="White" FontWeight="Bold" HorizontalAlignment="Center" VerticalAlignment="Center"/>
         </Border>
-        <Border Name="Rect7" Background="Blue" Height="50" RelativePanel.RightOf="{Binding ElementName=Rect1}">
+        <Border Name="Rect7" Background="Blue" Height="50" RelativePanel.RightOf="Rect1">
             <TextBlock Text="Rect7 (RightOf Rect1)" Padding="10,0" Foreground="White" FontWeight="Bold" HorizontalAlignment="Center" VerticalAlignment="Center"/>
         </Border>
-        <Border Name="Rect8" Background="Green" Height="50" RelativePanel.Below="{Binding ElementName=Rect7}">
+        <Border Name="Rect8" Background="Green" Height="50" RelativePanel.Below="Rect7">
             <TextBlock Text="Rect8 (Below Rect7)" Padding="10,0" Foreground="White" FontWeight="Bold" HorizontalAlignment="Center" VerticalAlignment="Center"/>
         </Border>
         <Border Name="Rect9" Background="Blue" Height="140" Width="460" RelativePanel.AlignHorizontalCenterWithPanel="True" RelativePanel.AlignVerticalCenterWithPanel="True">
             <TextBlock Text="Rect9" Padding="10" Foreground="White" FontWeight="Bold" HorizontalAlignment="Center" VerticalAlignment="Top"/>
         </Border>
-        <Border Name="Rect10" Background="Red" Width="50" RelativePanel.RightOf="{Binding ElementName=Rect9}" RelativePanel.AlignVerticalCenterWith="{Binding ElementName=Rect9}">
+        <Border Name="Rect10" Background="Red" Width="50" RelativePanel.RightOf="Rect9" RelativePanel.AlignVerticalCenterWith="Rect9">
             <TextBlock Text="Rect14 (RightOf Rect9, AlignVerticalCenterWith Rect9)" Padding="10,0" Foreground="White" FontWeight="Bold" HorizontalAlignment="Center" VerticalAlignment="Center">
                 <TextBlock.RenderTransform>
                     <TransformGroup>
@@ -41,19 +41,19 @@
                 </TextBlock.RenderTransform>
             </TextBlock>
         </Border>
-        <Border Name="Rect11" Background="Red" Height="50" RelativePanel.AlignBottomWith="{Binding ElementName=Rect9}" RelativePanel.AlignHorizontalCenterWith="{Binding ElementName=Rect9}">
+        <Border Name="Rect11" Background="Red" Height="50" RelativePanel.AlignBottomWith="Rect9" RelativePanel.AlignHorizontalCenterWith="Rect9">
             <TextBlock Text="Rect11 (AlignBottomWith Rect9, AlignHorizontalCenterWith Rect9)" Padding="10,0" Foreground="White" FontWeight="Bold" HorizontalAlignment="Center" VerticalAlignment="Center"/>
         </Border>
-        <Border Name="Rect12" Background="Red" Height="50" RelativePanel.Below="{Binding ElementName=Rect8}" RelativePanel.AlignLeftWith="{Binding ElementName=Rect7}">
+        <Border Name="Rect12" Background="Red" Height="50" RelativePanel.Below="Rect8" RelativePanel.AlignLeftWith="Rect7">
             <TextBlock Text="Rect12 (Below Rect8, AlignLeftWith Rect7)" Padding="10,0" Foreground="White" FontWeight="Bold" HorizontalAlignment="Center" VerticalAlignment="Center"/>
         </Border>
-        <Border Name="Rect13" Background="Blue" Height="50" RelativePanel.Below="{Binding ElementName=Rect12}" RelativePanel.AlignRightWith="{Binding ElementName=Rect12}">
+        <Border Name="Rect13" Background="Blue" Height="50" RelativePanel.Below="Rect12" RelativePanel.AlignRightWith="Rect12">
             <TextBlock Text="Rect13 (Below Rect12, AlignRightWith Rect12)" Padding="10,0" Foreground="White" FontWeight="Bold" HorizontalAlignment="Center" VerticalAlignment="Center"/>
         </Border>
-        <Border Name="Rect14" Background="Green" Height="50" RelativePanel.Above="{Binding ElementName=Rect9}" RelativePanel.AlignRightWith="{Binding ElementName=Rect9}">
+        <Border Name="Rect14" Background="Green" Height="50" RelativePanel.Above="Rect9" RelativePanel.AlignRightWith="Rect9">
             <TextBlock Text="Rect14 (Above Rect9, AlignRightWith Rect9)" Padding="10,0" Foreground="White" FontWeight="Bold" HorizontalAlignment="Center" VerticalAlignment="Center"/>
         </Border>
-        <Border Name="Rect15" Background="Red" Height="50" RelativePanel.LeftOf="{Binding ElementName=Rect2}" RelativePanel.AlignTopWith="{Binding ElementName=Rect9}">
+        <Border Name="Rect15" Background="Red" Height="50" RelativePanel.LeftOf="Rect2" RelativePanel.AlignTopWith="Rect9">
             <TextBlock Text="Rect15 (LeftOf Rect2, AlignTopWith Rect9)" Padding="10,0" Foreground="White" FontWeight="Bold" HorizontalAlignment="Center" VerticalAlignment="Center"/>
         </Border>
     </RelativePanel>

samples/ControlCatalog/Pages/SliderPage.xaml

@@ -1,5 +1,6 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:sys="clr-namespace:System;assembly=netstandard"
              x:Class="ControlCatalog.Pages.SliderPage">
   <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">Slider</TextBlock>
@@ -21,6 +22,15 @@
                 IsSnapToTickEnabled="True"
                 Ticks="0,20,25,40,75,100"
                 Width="300" />
+        <Slider Value="0"
+                Minimum="0"
+                Maximum="100"
+                TickFrequency="10"
+                Width="300">
+          <DataValidationErrors.Error>
+            <sys:Exception /> 
+          </DataValidationErrors.Error>
+        </Slider>
       </StackPanel>
       <Slider Value="0"
               Minimum="0"

samples/ControlCatalog/Pages/TextBlockPage.xaml

@@ -18,8 +18,8 @@
       </StackPanel.Styles>
       <Border>
         <StackPanel Width="200" Spacing="8">
-          <TextBlock TextTrimming="CharacterEllipsis" Text="Lorem ipsum dolor sit amet, consectetur adipiscing elit."/>
+          <TextBlock Margin="0 0 10 0" TextTrimming="CharacterEllipsis" Text="Lorem ipsum dolor sit amet, consectetur adipiscing elit."/>
-          <TextBlock TextTrimming="WordEllipsis" Text="Lorem ipsum dolor sit amet, consectetur adipiscing elit."/>
+          <TextBlock Margin="0 0 10 0" TextTrimming="WordEllipsis" Text="Lorem ipsum dolor sit amet, consectetur adipiscing elit."/>
           <TextBlock Text="Left aligned text" TextAlignment="Left" />
           <TextBlock Text="Center aligned text" TextAlignment="Center" />
           <TextBlock Text="Right aligned text" TextAlignment="Right" />

samples/ControlCatalog/Pages/TextBoxPage.xaml

@@ -1,9 +1,10 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             x:Class="ControlCatalog.Pages.TextBoxPage">
+             x:Class="ControlCatalog.Pages.TextBoxPage"
+             xmlns:sys="clr-namespace:System;assembly=netstandard">
   <StackPanel Orientation="Vertical" Spacing="4">
-    <TextBlock Classes="h1">TextBox</TextBlock>
+    <Label Classes="h1">TextBox</Label>
-    <TextBlock Classes="h2">A control into which the user can input text</TextBlock>
+    <Label Classes="h2">A control into which the user can input text</Label>
 
     <StackPanel Orientation="Horizontal"
               Margin="0,16,0,0"
@@ -11,12 +12,18 @@
               Spacing="16">
       <StackPanel Orientation="Vertical" Spacing="8">
         <TextBox Text="Lorem ipsum dolor sit amet, consectetur adipiscing elit." Width="200" />
-        <TextBox Watermark="ReadOnly" IsReadOnly="True" Text="This is read only"/>
+        <TextBox Width="200" Watermark="ReadOnly" IsReadOnly="True" Text="This is read only"/>
         <TextBox Width="200" Watermark="Watermark" />
         <TextBox Width="200"
                  Watermark="Floating Watermark"
                  UseFloatingWatermark="True"
                  Text="Lorem ipsum dolor sit amet, consectetur adipiscing elit."/>
+        
+        <TextBox Width="200" Text="Validation Error">
+          <DataValidationErrors.Error>
+            <sys:Exception /> 
+          </DataValidationErrors.Error>
+        </TextBox>
 
         <TextBox Width="200"
                  Watermark="Password Box"
@@ -38,24 +45,24 @@
                  Text="Multiline TextBox with TextWrapping.&#xD;&#xD;Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus magna. Cras in mi at felis aliquet congue. Ut a est eget ligula molestie gravida. Curabitur massa. Donec eleifend, libero at sagittis mollis, tellus est malesuada tellus, at luctus turpis elit sit amet quam. Vivamus pretium ornare est." />
         <TextBox AcceptsReturn="True" Width="200" Height="125"
                  Text="Multiline TextBox with no TextWrapping.&#xD;&#xD;Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus magna. Cras in mi at felis aliquet congue. Ut a est eget ligula molestie gravida. Curabitur massa. Donec eleifend, libero at sagittis mollis, tellus est malesuada tellus, at luctus turpis elit sit amet quam. Vivamus pretium ornare est." />
-        
+
         <TextBox Classes="clearButton" Text="Clear Content" Width="200" FontWeight="Normal" FontStyle="Normal" Watermark="Watermark" FontFamily="avares://ControlCatalog/Assets/Fonts#Source Sans Pro"/>
       </StackPanel>
-        <StackPanel Orientation="Vertical" Spacing="8">
+      <StackPanel Orientation="Vertical" Spacing="8">
-            <TextBlock Classes="h2">resm fonts</TextBlock>
+        <Label Classes="h2" Target="{Binding #firstResMFont}">res_m fonts</Label>
-            <TextBox Width="200" Text="Custom font regular" FontWeight="Normal" FontStyle="Normal" FontFamily="resm:ControlCatalog.Assets.Fonts?assembly=ControlCatalog#Source Sans Pro"/>
+        <TextBox Width="200" x:Name="firstResMFont" Text="Custom font regular" FontWeight="Normal" FontStyle="Normal" FontFamily="resm:ControlCatalog.Assets.Fonts?assembly=ControlCatalog#Source Sans Pro"/>
-                <TextBox Width="200" Text="Custom font bold" FontWeight="Bold" FontStyle="Normal" FontFamily="resm:ControlCatalog.Assets.Fonts?assembly=ControlCatalog#Source Sans Pro"/>
+        <TextBox Width="200" Text="Custom font bold" FontWeight="Bold" FontStyle="Normal" FontFamily="resm:ControlCatalog.Assets.Fonts?assembly=ControlCatalog#Source Sans Pro"/>
-                <TextBox Width="200" Text="Custom font italic" FontWeight="Normal" FontStyle="Italic" FontFamily="resm:ControlCatalog.Assets.Fonts.SourceSansPro-Italic.ttf?assembly=ControlCatalog#Source Sans Pro"/>
+        <TextBox Width="200" Text="Custom font italic" FontWeight="Normal" FontStyle="Italic" FontFamily="resm:ControlCatalog.Assets.Fonts.SourceSansPro-Italic.ttf?assembly=ControlCatalog#Source Sans Pro"/>
-                <TextBox Width="200" Text="Custom font italic bold" FontWeight="Bold" FontStyle="Italic" FontFamily="resm:ControlCatalog.Assets.Fonts.SourceSansPro-*.ttf?assembly=ControlCatalog#Source Sans Pro"/>
+        <TextBox Width="200" Text="Custom font italic bold" FontWeight="Bold" FontStyle="Italic" FontFamily="resm:ControlCatalog.Assets.Fonts.SourceSansPro-*.ttf?assembly=ControlCatalog#Source Sans Pro"/>
-        </StackPanel>
+      </StackPanel>
-        
+
-        <StackPanel Orientation="Vertical" Spacing="8">
+      <StackPanel Orientation="Vertical" Spacing="8">
-            <TextBlock Classes="h2">res fonts</TextBlock>
+        <Label Classes="h2" Target="{Binding #firstResFont}">_res fonts</Label>
-            <TextBox Width="200" Text="Custom font regular" FontWeight="Normal" FontStyle="Normal" FontFamily="avares://ControlCatalog/Assets/Fonts#Source Sans Pro"/>
+        <TextBox Width="200" x:Name="firstResFont" Text="Custom font regular" FontWeight="Normal" FontStyle="Normal" FontFamily="avares://ControlCatalog/Assets/Fonts#Source Sans Pro"/>
-            <TextBox Width="200" Text="Custom font bold" FontWeight="Bold" FontStyle="Normal" FontFamily="avares://ControlCatalog/Assets/Fonts#Source Sans Pro"/>
+        <TextBox Width="200" Text="Custom font bold" FontWeight="Bold" FontStyle="Normal" FontFamily="avares://ControlCatalog/Assets/Fonts#Source Sans Pro"/>
-            <TextBox Width="200" Text="Custom font italic" FontWeight="Normal" FontStyle="Italic" FontFamily="/Assets/Fonts/SourceSansPro-Italic.ttf#Source Sans Pro"/>
+        <TextBox Width="200" Text="Custom font italic" FontWeight="Normal" FontStyle="Italic" FontFamily="/Assets/Fonts/SourceSansPro-Italic.ttf#Source Sans Pro"/>
-            <TextBox Width="200" Text="Custom font italic bold" FontWeight="Bold" FontStyle="Italic" FontFamily="/Assets/Fonts/SourceSansPro-*.ttf#Source Sans Pro"/>
+        <TextBox Width="200" Text="Custom font italic bold" FontWeight="Bold" FontStyle="Italic" FontFamily="/Assets/Fonts/SourceSansPro-*.ttf#Source Sans Pro"/>
-        </StackPanel>
       </StackPanel>
+    </StackPanel>
   </StackPanel>
 </UserControl>

samples/Previewer/App.xaml.cs

@@ -1,4 +1,5 @@
 using Avalonia;
+using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Markup.Xaml;
 
 namespace Previewer
@@ -9,6 +10,13 @@ namespace Previewer
         {
             AvaloniaXamlLoader.Load(this);
         }
+
+        public override void OnFrameworkInitializationCompleted()
+        {
+            if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
+                desktop.MainWindow = new MainWindow();
+            base.OnFrameworkInitializationCompleted();
+        }
     }
 
-}
+}

samples/Previewer/Program.cs

@@ -1,13 +1,14 @@
-using System;
+using Avalonia;
-using Avalonia;
 
 namespace Previewer
 {
     class Program
     {
-        static void Main(string[] args)
+        public static AppBuilder BuildAvaloniaApp()
-        {
+          => AppBuilder.Configure<App>()
-            AppBuilder.Configure<App>().UsePlatformDetect().Start<MainWindow>();
+                .UsePlatformDetect();
-        }
+
+        public static int Main(string[] args)
+          => BuildAvaloniaApp().StartWithClassicDesktopLifetime(args);
     }
-}
+}

samples/RenderDemo/App.xaml.cs

@@ -1,4 +1,5 @@
 using Avalonia;
+using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Markup.Xaml;
 using Avalonia.ReactiveUI;
 
@@ -11,15 +12,27 @@ namespace RenderDemo
             AvaloniaXamlLoader.Load(this);
         }
 
+        public override void OnFrameworkInitializationCompleted()
+        {
+            if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
+                desktop.MainWindow = new MainWindow();
+            base.OnFrameworkInitializationCompleted();
+        }
+
         // TODO: Make this work with GTK/Skia/Cairo depending on command-line args
         // again.
-        static void Main(string[] args) => BuildAvaloniaApp().Start<MainWindow>();
+        static void Main(string[] args) 
+            => BuildAvaloniaApp().StartWithClassicDesktopLifetime(args);
 
         // App configuration, used by the entry point and previewer
         static AppBuilder BuildAvaloniaApp()
            => AppBuilder.Configure<App>()
+               .With(new Win32PlatformOptions
+               {
+                   OverlayPopups = true,
+               })
                 .UsePlatformDetect()
                 .UseReactiveUI()
-                .LogToDebug();
+                .LogToTrace();
     }
 }

samples/RenderDemo/MainWindow.xaml

@@ -3,8 +3,8 @@
         x:Class="RenderDemo.MainWindow"
         Title="AvaloniaUI Rendering Test"
         xmlns:pages="clr-namespace:RenderDemo.Pages"
-        Width="800"
+        Width="{Binding Width, Mode=TwoWay}"
-        Height="600">
+        Height="{Binding Height, Mode=TwoWay}">
   <DockPanel>
     <Menu DockPanel.Dock="Top">
       <MenuItem Header="Rendering">
@@ -24,6 +24,10 @@
           </MenuItem.Icon>
         </MenuItem>
       </MenuItem>
+      <MenuItem Header="Tests">
+        <MenuItem Header="Resize window"
+                  Command="{Binding ResizeWindow}"/>
+      </MenuItem>
     </Menu>
     <TabControl Classes="sidebar">
       <TabItem Header="Animations">

samples/RenderDemo/Pages/GlyphRunPage.xaml

@@ -6,9 +6,9 @@
              x:Class="RenderDemo.Pages.GlyphRunPage">
   <Border
     Background="White">
-    <DrawingPresenter
+    <Image
-      x:Name="drawingPresenter"
+      x:Name="imageControl"
       Stretch="None">
-    </DrawingPresenter>
+    </Image>
   </Border>
 </UserControl>

samples/RenderDemo/Pages/GlyphRunPage.xaml.cs

@@ -9,7 +9,7 @@ namespace RenderDemo.Pages
 {
     public class GlyphRunPage : UserControl
     {
-        private DrawingPresenter _drawingPresenter;
+        private Image _imageControl;
         private GlyphTypeface _glyphTypeface = Typeface.Default.GlyphTypeface;
         private readonly Random _rand = new Random();
         private ushort[] _glyphIndices = new ushort[1];
@@ -25,7 +25,8 @@ namespace RenderDemo.Pages
         {
             AvaloniaXamlLoader.Load(this);
 
-            _drawingPresenter = this.FindControl<DrawingPresenter>("drawingPresenter");
+            _imageControl = this.FindControl<Image>("imageControl");
+            _imageControl.Source = new DrawingImage();
 
             DispatcherTimer.Run(() =>
             {
@@ -61,7 +62,6 @@ namespace RenderDemo.Pages
             {
                 Foreground = Brushes.Black,
                 GlyphRun = new GlyphRun(_glyphTypeface, _fontSize, _glyphIndices),
-                BaselineOrigin = new Point(0, -_glyphTypeface.Ascent * scale)
             };
 
             drawingGroup.Children.Add(glyphRunDrawing);
@@ -69,12 +69,12 @@ namespace RenderDemo.Pages
             var geometryDrawing = new GeometryDrawing
             {
                 Pen = new Pen(Brushes.Black),
-                Geometry = new RectangleGeometry { Rect = glyphRunDrawing.GlyphRun.Bounds }
+                Geometry = new RectangleGeometry { Rect = new Rect(glyphRunDrawing.GlyphRun.Size) }
             };
 
             drawingGroup.Children.Add(geometryDrawing);
 
-            _drawingPresenter.Drawing = drawingGroup;
+            (_imageControl.Source as DrawingImage).Drawing = drawingGroup;
         }
     }
 }

samples/RenderDemo/ViewModels/MainWindowViewModel.cs

@@ -1,5 +1,6 @@
-using System;
+using System.Reactive;
-using System.Reactive;
+using System.Threading.Tasks;
+
 using ReactiveUI;
 
 namespace RenderDemo.ViewModels
@@ -8,26 +9,61 @@ namespace RenderDemo.ViewModels
     {
         private bool drawDirtyRects = false;
         private bool drawFps = true;
+        private double width = 800;
+        private double height = 600;
 
         public MainWindowViewModel()
         {
             ToggleDrawDirtyRects = ReactiveCommand.Create(() => DrawDirtyRects = !DrawDirtyRects);
             ToggleDrawFps = ReactiveCommand.Create(() => DrawFps = !DrawFps);
+            ResizeWindow = ReactiveCommand.CreateFromTask(ResizeWindowAsync);
         }
 
         public bool DrawDirtyRects
         {
-            get { return drawDirtyRects; }
+            get => drawDirtyRects;
-            set { this.RaiseAndSetIfChanged(ref drawDirtyRects, value); }
+            set => this.RaiseAndSetIfChanged(ref drawDirtyRects, value);
         }
 
         public bool DrawFps
         {
-            get { return drawFps; }
+            get => drawFps;
-            set { this.RaiseAndSetIfChanged(ref drawFps, value); }
+            set => this.RaiseAndSetIfChanged(ref drawFps, value);
+        }
+
+        public double Width
+        {
+            get => width;
+            set => this.RaiseAndSetIfChanged(ref width, value);
+        }
+
+        public double Height
+        {
+            get => height;
+            set => this.RaiseAndSetIfChanged(ref height, value);
         }
 
         public ReactiveCommand<Unit, bool> ToggleDrawDirtyRects { get; }
         public ReactiveCommand<Unit, bool> ToggleDrawFps { get; }
+        public ReactiveCommand<Unit, Unit> ResizeWindow { get; }
+
+        private async Task ResizeWindowAsync()
+        {
+            for (int i = 0; i < 30; i++)
+            {
+                Width += 10;
+                Height += 5;
+                await Task.Delay(10);
+            }
+
+            await Task.Delay(10);
+
+            for (int i = 0; i < 30; i++)
+            {
+                Width -= 10;
+                Height -= 5;
+                await Task.Delay(10);
+            }
+        }
     }
 }

samples/Sandbox/Program.cs

@@ -10,7 +10,7 @@ namespace Sandbox
             AppBuilder.Configure<App>()
                 .UsePlatformDetect()
                 .UseReactiveUI()
-                .LogToDebug()
+                .LogToTrace()
                 .StartWithClassicDesktopLifetime(args);
         }
     }

samples/VirtualizationDemo/App.xaml.cs

@@ -1,4 +1,5 @@
 using Avalonia;
+using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Markup.Xaml;
 
 namespace VirtualizationDemo
@@ -9,5 +10,12 @@ namespace VirtualizationDemo
         {
             AvaloniaXamlLoader.Load(this);
         }
+
+        public override void OnFrameworkInitializationCompleted()
+        {
+            if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
+                desktop.MainWindow = new MainWindow();
+            base.OnFrameworkInitializationCompleted();
+        }
     }
 }

samples/VirtualizationDemo/Program.cs

@@ -1,19 +1,17 @@
-using System;
+using Avalonia;
-using Avalonia;
-using Avalonia.Controls;
 using Avalonia.ReactiveUI;
 
 namespace VirtualizationDemo
 {
     class Program
     {
-        static void Main(string[] args)
+        public static AppBuilder BuildAvaloniaApp()
-        {
+            => AppBuilder.Configure<App>()
-            AppBuilder.Configure<App>()
+                .UsePlatformDetect()
-               .UsePlatformDetect()
+                .UseReactiveUI()
-               .UseReactiveUI()
+                .LogToTrace();
-               .LogToDebug()
+
-               .Start<MainWindow>();
+        public static int Main(string[] args)
-        }
+            => BuildAvaloniaApp().StartWithClassicDesktopLifetime(args);
     }
 }

samples/interop/Direct3DInteropSample/App.paml.cs

@@ -1,4 +1,5 @@
 using Avalonia;
+using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Markup.Xaml;
 
 namespace Direct3DInteropSample
@@ -9,5 +10,12 @@ namespace Direct3DInteropSample
         {
             AvaloniaXamlLoader.Load(this);
         }
+
+        public override void OnFrameworkInitializationCompleted()
+        {
+            if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
+                desktop.MainWindow = new MainWindow();
+            base.OnFrameworkInitializationCompleted();
+        }
     }
 }

samples/interop/Direct3DInteropSample/Program.cs

@@ -1,19 +1,16 @@
-using System;
+using Avalonia;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-using Avalonia;
 
 namespace Direct3DInteropSample
 {
     class Program
     {
-        static void Main(string[] args)
+        public static AppBuilder BuildAvaloniaApp()
-        {
+            => AppBuilder.Configure<App>()
-            AppBuilder.Configure<App>()
+                .With(new Win32PlatformOptions { UseDeferredRendering = false })
-                .With(new Win32PlatformOptions {UseDeferredRendering = false})
+                .UseWin32()
-                .UseWin32().UseDirect2D1().Start<MainWindow>();
+                .UseDirect2D1();
-        }
+
+        public static int Main(string[] args)
+            => BuildAvaloniaApp().StartWithClassicDesktopLifetime(args);
     }
 }

samples/interop/NativeEmbedSample/NativeEmbedSample.csproj

@@ -9,11 +9,10 @@
 
   <ItemGroup>
     <PackageReference Include="MonoMac.NetStandard" Version="0.0.4" />
-    <ProjectReference Include="..\..\..\src\Avalonia.Desktop\Avalonia.Desktop.csproj" />
     <ProjectReference Include="..\..\..\src\Windows\Avalonia.Direct2D1\Avalonia.Direct2D1.csproj" />
     <ProjectReference Include="..\..\..\src\Avalonia.Diagnostics\Avalonia.Diagnostics.csproj" />
     <ProjectReference Include="..\..\..\src\Avalonia.X11\Avalonia.X11.csproj" />
-    <PackageReference Include="Avalonia.Angle.Windows.Natives" Version="2.1.0.2019013001" />
+    <PackageReference Include="Avalonia.Angle.Windows.Natives" Version="2.1.0.2020091801" />
 
     <AvaloniaResource Include="**\*.xaml">
       <SubType>Designer</SubType>

src/Avalonia.Animation/KeySplineTypeConverter.cs

@@ -19,7 +19,7 @@ namespace Avalonia.Animation
 
         public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
         {
-            return KeySpline.Parse((string)value, culture);
+            return KeySpline.Parse((string)value, CultureInfo.InvariantCulture);
         }
     }
 }

src/Avalonia.Animation/Properties/AssemblyInfo.cs

@@ -6,5 +6,10 @@ using System.Runtime.CompilerServices;
 [assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Animation.Easings")]
 [assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Animation.Animators")]
 
+#if SIGNED_BUILD
+[assembly: InternalsVisibleTo("Avalonia.LeakTests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c1bba1142285fe0419326fb25866ba62c47e6c2b5c1ab0c95b46413fad375471232cb81706932e1cef38781b9ebd39d5100401bacb651c6c5bbf59e571e81b3bc08d2a622004e08b1a6ece82a7e0b9857525c86d2b95fab4bc3dce148558d7f3ae61aa3a234086902aeface87d9dfdd32b9d2fe3c6dd4055b5ab4b104998bd87")]
+[assembly: InternalsVisibleTo("Avalonia.Animation.UnitTests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c1bba1142285fe0419326fb25866ba62c47e6c2b5c1ab0c95b46413fad375471232cb81706932e1cef38781b9ebd39d5100401bacb651c6c5bbf59e571e81b3bc08d2a622004e08b1a6ece82a7e0b9857525c86d2b95fab4bc3dce148558d7f3ae61aa3a234086902aeface87d9dfdd32b9d2fe3c6dd4055b5ab4b104998bd87")]
+#else
 [assembly: InternalsVisibleTo("Avalonia.LeakTests")]
 [assembly: InternalsVisibleTo("Avalonia.Animation.UnitTests")]
+#endif

src/Avalonia.Base/ApiCompatBaseline.txt

@@ -0,0 +1,4 @@
+Compat issues with assembly Avalonia.Base:
+CannotAddAbstractMembers : Member 'protected System.IObservable<Avalonia.AvaloniaPropertyChangedEventArgs> Avalonia.AvaloniaProperty.GetChanged()' is abstract in the implementation but is missing in the contract.
+TypesMustExist : Type 'Avalonia.Logging.DebugLogSink' does not exist in the implementation but it does exist in the contract.
+Total Issues: 2

src/Avalonia.Base/AvaloniaLocator.cs

@@ -54,6 +54,23 @@ namespace Avalonia
                 return _locator;
             }
 
+            public AvaloniaLocator ToLazy<TImlp>(Func<TImlp> func) where TImlp : TService
+            {
+                var constructed = false;
+                TImlp instance = default;
+                _locator._registry[typeof (TService)] = () =>
+                {
+                    if (!constructed)
+                    {
+                        instance = func();
+                        constructed = true;
+                    }
+
+                    return instance;
+                };
+                return _locator;
+            }
+            
             public AvaloniaLocator ToSingleton<TImpl>() where TImpl : class, TService, new()
             {
                 TImpl instance = null;

src/Avalonia.Base/AvaloniaObject.cs

@@ -113,16 +113,8 @@ namespace Avalonia
         /// <param name="binding">The binding information.</param>
         public IBinding this[IndexerDescriptor binding]
         {
-            get
+            get { return new IndexerBinding(this, binding.Property, binding.Mode); }
-            {
+            set { this.Bind(binding.Property, value); }
-                return new IndexerBinding(this, binding.Property, binding.Mode);
-            }
-
-            set
-            {
-                var sourceBinding = value as IBinding;
-                this.Bind(binding.Property, sourceBinding);
-            }
         }
 
         public bool CheckAccess() => Dispatcher.UIThread.CheckAccess();

src/Avalonia.Base/AvaloniaProperty.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Reactive.Subjects;
 using Avalonia.Data;
 using Avalonia.Data.Core;
 using Avalonia.Utilities;
@@ -18,7 +17,6 @@ namespace Avalonia
         public static readonly object UnsetValue = new UnsetValueType();
 
         private static int s_nextId;
-        private readonly Subject<AvaloniaPropertyChangedEventArgs> _changed;
         private readonly PropertyMetadata _defaultMetadata;
         private readonly Dictionary<Type, PropertyMetadata> _metadata;
         private readonly Dictionary<Type, PropertyMetadata> _metadataCache = new Dictionary<Type, PropertyMetadata>();
@@ -50,7 +48,6 @@ namespace Avalonia
                 throw new ArgumentException("'name' may not contain periods.");
             }
 
-            _changed = new Subject<AvaloniaPropertyChangedEventArgs>();
             _metadata = new Dictionary<Type, PropertyMetadata>();
 
             Name = name;
@@ -77,7 +74,6 @@ namespace Avalonia
             Contract.Requires<ArgumentNullException>(source != null);
             Contract.Requires<ArgumentNullException>(ownerType != null);
 
-            _changed = source._changed;
             _metadata = new Dictionary<Type, PropertyMetadata>();
 
             Name = source.Name;
@@ -139,7 +135,7 @@ namespace Avalonia
         /// An observable that is fired when this property changes on any
         /// <see cref="AvaloniaObject"/> instance.
         /// </value>
-        public IObservable<AvaloniaPropertyChangedEventArgs> Changed => _changed;
+        public IObservable<AvaloniaPropertyChangedEventArgs> Changed => GetChanged();
 
         /// <summary>
         /// Gets a method that gets called before and after the property starts being notified on an
@@ -474,15 +470,6 @@ namespace Avalonia
         public abstract void Accept<TData>(IAvaloniaPropertyVisitor<TData> vistor, ref TData data)
             where TData : struct;
 
-        /// <summary>
-        /// Notifies the <see cref="Changed"/> observable.
-        /// </summary>
-        /// <param name="e">The observable arguments.</param>
-        internal void NotifyChanged(AvaloniaPropertyChangedEventArgs e)
-        {
-            _changed.OnNext(e);
-        }
-
         /// <summary>
         /// Routes an untyped ClearValue call to a typed call.
         /// </summary>
@@ -553,6 +540,8 @@ namespace Avalonia
             _hasMetadataOverrides = true;
         }
 
+        protected abstract IObservable<AvaloniaPropertyChangedEventArgs> GetChanged();
+
         private PropertyMetadata GetMetadataWithOverrides(Type type)
         {
             if (type is null)

src/Avalonia.Base/AvaloniaProperty`1.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Reactive.Subjects;
 using Avalonia.Data;
 using Avalonia.Utilities;
 
@@ -10,6 +11,8 @@ namespace Avalonia
     /// <typeparam name="TValue">The value type of the property.</typeparam>
     public abstract class AvaloniaProperty<TValue> : AvaloniaProperty
     {
+        private readonly Subject<AvaloniaPropertyChangedEventArgs<TValue>> _changed;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="AvaloniaProperty{TValue}"/> class.
         /// </summary>
@@ -24,22 +27,61 @@ namespace Avalonia
             Action<IAvaloniaObject, bool> notifying = null)
             : base(name, typeof(TValue), ownerType, metadata, notifying)
         {
+            _changed = new Subject<AvaloniaPropertyChangedEventArgs<TValue>>();
         }
 
         /// <summary>
-        /// Initializes a new instance of the <see cref="AvaloniaProperty"/> class.
+        /// Initializes a new instance of the <see cref="AvaloniaProperty{TValue}"/> class.
         /// </summary>
         /// <param name="source">The property to copy.</param>
         /// <param name="ownerType">The new owner type.</param>
         /// <param name="metadata">Optional overridden metadata.</param>
+        [Obsolete("Use constructor with AvaloniaProperty<TValue> instead.", true)]
         protected AvaloniaProperty(
-            AvaloniaProperty source, 
+            AvaloniaProperty source,
-            Type ownerType, 
+            Type ownerType,
+            PropertyMetadata metadata)
+            : this(source as AvaloniaProperty<TValue> ?? throw new InvalidOperationException(), ownerType, metadata)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="AvaloniaProperty{TValue}"/> class.
+        /// </summary>
+        /// <param name="source">The property to copy.</param>
+        /// <param name="ownerType">The new owner type.</param>
+        /// <param name="metadata">Optional overridden metadata.</param>
+        protected AvaloniaProperty(
+            AvaloniaProperty<TValue> source,
+            Type ownerType,
             PropertyMetadata metadata)
             : base(source, ownerType, metadata)
         {
+            _changed = source._changed;
+        }
+
+        /// <summary>
+        /// Gets an observable that is fired when this property changes on any
+        /// <see cref="AvaloniaObject"/> instance.
+        /// </summary>
+        /// <value>
+        /// An observable that is fired when this property changes on any
+        /// <see cref="AvaloniaObject"/> instance.
+        /// </value>
+
+        public new IObservable<AvaloniaPropertyChangedEventArgs<TValue>> Changed => _changed;
+
+        /// <summary>
+        /// Notifies the <see cref="Changed"/> observable.
+        /// </summary>
+        /// <param name="e">The observable arguments.</param>
+        internal void NotifyChanged(AvaloniaPropertyChangedEventArgs<TValue> e)
+        {
+            _changed.OnNext(e);
         }
 
+        protected override IObservable<AvaloniaPropertyChangedEventArgs> GetChanged() => Changed;
+
         protected BindingValue<object> TryConvert(object value)
         {
             if (value == UnsetValue)

src/Avalonia.Base/Data/Core/Plugins/DataAnnotationsValidationPlugin.cs

@@ -63,12 +63,12 @@ namespace Avalonia.Data.Core.Plugins
             {
                 if (errors.Count == 1)
                 {
-                    return new ValidationException(errors[0].ErrorMessage);
+                    return new DataValidationException(errors[0].ErrorMessage);
                 }
                 else
                 {
                     return new AggregateException(
-                        errors.Select(x => new ValidationException(x.ErrorMessage)));
+                        errors.Select(x => new DataValidationException(x.ErrorMessage)));
                 }
             }
         }

src/Avalonia.Base/Data/Core/Plugins/InpcPropertyAccessorPlugin.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.ComponentModel;
 using System.Reflection;
 using Avalonia.Utilities;
@@ -11,8 +12,11 @@ namespace Avalonia.Data.Core.Plugins
     /// </summary>
     public class InpcPropertyAccessorPlugin : IPropertyAccessorPlugin
     {
+        private readonly Dictionary<(Type, string), PropertyInfo> _propertyLookup =
+            new Dictionary<(Type, string), PropertyInfo>();
+        
         /// <inheritdoc/>
-        public bool Match(object obj, string propertyName) => GetPropertyWithName(obj.GetType(), propertyName) != null;
+        public bool Match(object obj, string propertyName) => GetFirstPropertyWithName(obj.GetType(), propertyName) != null;
 
         /// <summary>
         /// Starts monitoring the value of a property on an object.
@@ -30,7 +34,7 @@ namespace Avalonia.Data.Core.Plugins
 
             reference.TryGetTarget(out object instance);
 
-            var p = GetPropertyWithName(instance.GetType(), propertyName);
+            var p = GetFirstPropertyWithName(instance.GetType(), propertyName);
 
             if (p != null)
             {
@@ -44,12 +48,40 @@ namespace Avalonia.Data.Core.Plugins
             }
         }
 
-        private static PropertyInfo GetPropertyWithName(Type type, string propertyName)
+        private PropertyInfo GetFirstPropertyWithName(Type type, string propertyName)
         {
-            const BindingFlags bindingFlags = BindingFlags.NonPublic | BindingFlags.Public |
+            var key = (type, propertyName);
-                                              BindingFlags.Static | BindingFlags.Instance;
+            
+            if (!_propertyLookup.TryGetValue(key, out PropertyInfo propertyInfo))
+            {
+                propertyInfo = TryFindAndCacheProperty(type, propertyName);
+            }
+
+            return propertyInfo;
+        }
+        
+        private PropertyInfo TryFindAndCacheProperty(Type type, string propertyName)
+        {
+            PropertyInfo found = null;
+
+            const BindingFlags bindingFlags =
+                BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static | BindingFlags.Instance;
+
+            var properties = type.GetProperties(bindingFlags);
+
+            foreach (PropertyInfo propertyInfo in properties)
+            {
+                if (propertyInfo.Name == propertyName)
+                {
+                    found = propertyInfo;
+
+                    break;
+                }
+            }
+
+            _propertyLookup.Add((type, propertyName), found);
 
-            return type.GetProperty(propertyName, bindingFlags);
+            return found;
         }
 
         private class Accessor : PropertyAccessorBase, IWeakSubscriber<PropertyChangedEventArgs>

src/Avalonia.Base/DirectPropertyBase.cs

@@ -32,15 +32,30 @@ namespace Avalonia
         }
 
         /// <summary>
-        /// Initializes a new instance of the <see cref="AvaloniaProperty"/> class.
+        /// Initializes a new instance of the <see cref="DirectPropertyBase{TValue}"/> class.
         /// </summary>
         /// <param name="source">The property to copy.</param>
         /// <param name="ownerType">The new owner type.</param>
         /// <param name="metadata">Optional overridden metadata.</param>
+        [Obsolete("Use constructor with DirectPropertyBase<TValue> instead.", true)]
         protected DirectPropertyBase(
             AvaloniaProperty source,
             Type ownerType,
             PropertyMetadata metadata)
+            : this(source as DirectPropertyBase<TValue> ?? throw new InvalidOperationException(), ownerType, metadata)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DirectPropertyBase{TValue}"/> class.
+        /// </summary>
+        /// <param name="source">The property to copy.</param>
+        /// <param name="ownerType">The new owner type.</param>
+        /// <param name="metadata">Optional overridden metadata.</param>
+        protected DirectPropertyBase(
+            DirectPropertyBase<TValue> source,
+            Type ownerType,
+            PropertyMetadata metadata)
             : base(source, ownerType, metadata)
         {
         }

src/Avalonia.Base/Logging/DebugLogSink.cs → src/Avalonia.Base/Logging/TraceLogSink.cs

@@ -6,12 +6,12 @@ using Avalonia.Utilities;
 
 namespace Avalonia.Logging
 {
-    public class DebugLogSink : ILogSink
+    public class TraceLogSink : ILogSink
     {
         private readonly LogEventLevel _level;
         private readonly IList<string> _areas;
 
-        public DebugLogSink(
+        public TraceLogSink(
             LogEventLevel minimumLevel,
             IList<string> areas = null)
         {
@@ -28,7 +28,7 @@ namespace Avalonia.Logging
         {
             if (IsEnabled(level, area))
             {
-                Debug.WriteLine(Format<object, object, object>(area, messageTemplate, source));
+                Trace.WriteLine(Format<object, object, object>(area, messageTemplate, source));
             }
         }
 
@@ -36,7 +36,7 @@ namespace Avalonia.Logging
         {
             if (IsEnabled(level, area))
             {
-                Debug.WriteLine(Format<T0, object, object>(area, messageTemplate, source, propertyValue0));
+                Trace.WriteLine(Format<T0, object, object>(area, messageTemplate, source, propertyValue0));
             }
         }
 
@@ -44,7 +44,7 @@ namespace Avalonia.Logging
         {
             if (IsEnabled(level, area))
             {
-                Debug.WriteLine(Format<T0, T1, object>(area, messageTemplate, source, propertyValue0, propertyValue1));
+                Trace.WriteLine(Format<T0, T1, object>(area, messageTemplate, source, propertyValue0, propertyValue1));
             }
         }
 
@@ -52,7 +52,7 @@ namespace Avalonia.Logging
         {
             if (IsEnabled(level, area))
             {
-                Debug.WriteLine(Format(area, messageTemplate, source, propertyValue0, propertyValue1, propertyValue2));
+                Trace.WriteLine(Format(area, messageTemplate, source, propertyValue0, propertyValue1, propertyValue2));
             }
         }
 
@@ -60,7 +60,7 @@ namespace Avalonia.Logging
         {
             if (IsEnabled(level, area))
             {
-                Debug.WriteLine(Format(area, messageTemplate, source, propertyValues));
+                Trace.WriteLine(Format(area, messageTemplate, source, propertyValues));
             }
         }
 

src/Avalonia.Base/Metadata/XmlnsPrefixAttribute.cs

@@ -0,0 +1,39 @@
+using System;
+
+namespace Avalonia.Metadata
+{
+    /// <summary>
+    /// Use to predefine the prefix associated to an xml namespace in a xaml file
+    /// </summary>
+    /// <remarks>
+    /// example:
+    /// [assembly: XmlnsPrefix("https://github.com/avaloniaui", "av")]
+    /// xaml:
+    /// xmlns:av="https://github.com/avaloniaui"
+    /// </remarks>
+    [AttributeUsage(AttributeTargets.Assembly, AllowMultiple = true)]
+    public sealed class XmlnsPrefixAttribute : Attribute
+    {
+        /// <summary>
+        /// Constructor
+        /// </summary>
+        /// <param name="xmlNamespace">XML namespce</param>
+        /// <param name="prefix">recommended prefix</param>
+        public XmlnsPrefixAttribute(string xmlNamespace, string prefix)
+        {
+            XmlNamespace = xmlNamespace ?? throw new ArgumentNullException(nameof(xmlNamespace));
+
+            Prefix = prefix ?? throw new ArgumentNullException(nameof(prefix));
+        }
+
+        /// <summary>
+        /// XML Namespace
+        /// </summary>
+        public string XmlNamespace { get; }
+
+        /// <summary>
+        /// New Xml Namespace
+        /// </summary>
+        public string Prefix { get; }
+    }
+}

src/Avalonia.Base/Properties/AssemblyInfo.cs

@@ -5,8 +5,16 @@ using System.Runtime.CompilerServices;
 using Avalonia.Metadata;
 
 [assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Data.Converters")]
+#if SIGNED_BUILD
+[assembly: InternalsVisibleTo("Avalonia.Base.UnitTests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c1bba1142285fe0419326fb25866ba62c47e6c2b5c1ab0c95b46413fad375471232cb81706932e1cef38781b9ebd39d5100401bacb651c6c5bbf59e571e81b3bc08d2a622004e08b1a6ece82a7e0b9857525c86d2b95fab4bc3dce148558d7f3ae61aa3a234086902aeface87d9dfdd32b9d2fe3c6dd4055b5ab4b104998bd87")]
+[assembly: InternalsVisibleTo("Avalonia.UnitTests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c1bba1142285fe0419326fb25866ba62c47e6c2b5c1ab0c95b46413fad375471232cb81706932e1cef38781b9ebd39d5100401bacb651c6c5bbf59e571e81b3bc08d2a622004e08b1a6ece82a7e0b9857525c86d2b95fab4bc3dce148558d7f3ae61aa3a234086902aeface87d9dfdd32b9d2fe3c6dd4055b5ab4b104998bd87")]
+[assembly: InternalsVisibleTo("DynamicProxyGenAssembly2, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c547cac37abd99c8db225ef2f6c8a3602f3b3606cc9891605d02baa56104f4cfc0734aa39b93bf7852f7d9266654753cc297e7d2edfe0bac1cdcf9f717241550e0a7b191195b7667bb4f64bcb8e2121380fd1d9d46ad2d92d2d15605093924cceaf74c4861eff62abf69b9291ed0a340e113be11e6a7d3113e92484cf7045cc7")] 
+[assembly: InternalsVisibleTo("Avalonia.Controls.DataGrid, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c1bba1142285fe0419326fb25866ba62c47e6c2b5c1ab0c95b46413fad375471232cb81706932e1cef38781b9ebd39d5100401bacb651c6c5bbf59e571e81b3bc08d2a622004e08b1a6ece82a7e0b9857525c86d2b95fab4bc3dce148558d7f3ae61aa3a234086902aeface87d9dfdd32b9d2fe3c6dd4055b5ab4b104998bd87")]
+[assembly: InternalsVisibleTo("Avalonia.Markup.Xaml.UnitTests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c1bba1142285fe0419326fb25866ba62c47e6c2b5c1ab0c95b46413fad375471232cb81706932e1cef38781b9ebd39d5100401bacb651c6c5bbf59e571e81b3bc08d2a622004e08b1a6ece82a7e0b9857525c86d2b95fab4bc3dce148558d7f3ae61aa3a234086902aeface87d9dfdd32b9d2fe3c6dd4055b5ab4b104998bd87")]
+#else
 [assembly: InternalsVisibleTo("Avalonia.Base.UnitTests")]
 [assembly: InternalsVisibleTo("Avalonia.UnitTests")]
 [assembly: InternalsVisibleTo("DynamicProxyGenAssembly2")]
 [assembly: InternalsVisibleTo("Avalonia.Controls.DataGrid")]
 [assembly: InternalsVisibleTo("Avalonia.Markup.Xaml.UnitTests")]
+#endif

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

@@ -59,7 +59,7 @@
       </Compile>
       <Compile Remove="../Markup/Avalonia.Markup.Xaml.Loader\xamlil.github\**\obj\**\*.cs" />
       <Compile Remove="../Markup/Avalonia.Markup.Xaml.Loader\xamlil.github\src\XamlX\IL\SreTypeSystem.cs" />
-      <PackageReference Include="Avalonia.Unofficial.Cecil" Version="20190417.2.0" PrivateAssets="All" />
+      <PackageReference Include="Mono.Cecil" Version="0.11.2" />
       <PackageReference Include="Microsoft.Build.Framework" Version="15.1.548" PrivateAssets="All" />
     </ItemGroup>
 </Project>

src/Avalonia.Build.Tasks/CompileAvaloniaXamlTask.cs

@@ -39,7 +39,9 @@ namespace Avalonia.Build.Tasks
 
             var res = XamlCompilerTaskExecutor.Compile(BuildEngine, input,
                 File.ReadAllLines(ReferencesFilePath).Where(l => !string.IsNullOrWhiteSpace(l)).ToArray(),
-                ProjectDirectory, OutputPath, VerifyIl, outputImportance);
+                ProjectDirectory, OutputPath, VerifyIl, outputImportance,
+                (SignAssembly && !DelaySign) ? AssemblyOriginatorKeyFile : null
+                );
             if (!res.Success)
                 return false;
             if (!res.WrittenFile)
@@ -73,6 +75,10 @@ namespace Avalonia.Build.Tasks
         public string OutputPath { get; set; }
 
         public bool VerifyIl { get; set; }
+        
+        public string AssemblyOriginatorKeyFile { get; set; }
+        public bool SignAssembly { get; set; }
+        public bool DelaySign { get; set; }
 
         public string ReportImportance { get; set; }
 

src/Avalonia.Build.Tasks/XamlCompilerTaskExecutor.cs

@@ -42,7 +42,7 @@ namespace Avalonia.Build.Tasks
         }
         
         public static CompileResult Compile(IBuildEngine engine, string input, string[] references, string projectDirectory,
-            string output, bool verifyIl, MessageImportance logImportance)
+            string output, bool verifyIl, MessageImportance logImportance, string strongNameKey)
         {
             var typeSystem = new CecilTypeSystem(references.Concat(new[] {input}), input);
             var asm = typeSystem.TargetAssemblyDefinition;
@@ -345,6 +345,20 @@ namespace Avalonia.Build.Tasks
                     }
                     res.Remove();
                 }
+                
+                
+                // Technically that's a hack, but it fixes corert incompatibility caused by deterministic builds
+                int dupeCounter = 1;
+                foreach (var grp in typeDef.NestedTypes.GroupBy(x => x.Name))
+                {
+                    if (grp.Count() > 1)
+                    {
+                        foreach (var dupe in grp)
+                            dupe.Name += "_dup" + dupeCounter++;
+                    }
+                }
+                
+                
                 return true;
             }
             
@@ -361,10 +375,12 @@ namespace Avalonia.Build.Tasks
             loaderDispatcherMethod.Body.Instructions.Add(Instruction.Create(OpCodes.Ldnull));
             loaderDispatcherMethod.Body.Instructions.Add(Instruction.Create(OpCodes.Ret));
             
-            asm.Write(output, new WriterParameters
+            
-            {
+            var writerParameters = new WriterParameters { WriteSymbols = asm.MainModule.HasSymbols };
-                WriteSymbols = asm.MainModule.HasSymbols
+            if (!string.IsNullOrWhiteSpace(strongNameKey))
-            });
+                writerParameters.StrongNameKeyBlob = File.ReadAllBytes(strongNameKey);
+
+            asm.Write(output, writerParameters);
 
             return new CompileResult(true, true);
         }

src/Avalonia.Controls.DataGrid/ApiCompatBaseline.txt

@@ -0,0 +1,5 @@
+Compat issues with assembly Avalonia.Controls.DataGrid:
+MembersMustExist : Member 'public Avalonia.StyledProperty<System.String> Avalonia.StyledProperty<System.String> Avalonia.Controls.DataGridTextColumn.FontFamilyProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.String Avalonia.Controls.DataGridTextColumn.FontFamily.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public void Avalonia.Controls.DataGridTextColumn.FontFamily.set(System.String)' does not exist in the implementation but it does exist in the contract.
+Total Issues: 3

src/Avalonia.Controls.DataGrid/DataGrid.cs

@@ -24,12 +24,14 @@ using Avalonia.Input.Platform;
 using System.ComponentModel.DataAnnotations;
 using Avalonia.Controls.Utils;
 using Avalonia.Layout;
+using Avalonia.Controls.Metadata;
 
 namespace Avalonia.Controls
 {
     /// <summary>
     /// Displays data in a customizable grid.
     /// </summary>
+    [PseudoClasses(":invalid", ":empty-rows", ":empty-columns")]
     public partial class DataGrid : TemplatedControl
     {
         private const string DATAGRID_elementRowsPresenterName = "PART_RowsPresenter";
@@ -709,6 +711,7 @@ namespace Avalonia.Controls
 
             DisplayData = new DataGridDisplayData(this);
             ColumnsInternal = CreateColumnsInstance();
+            ColumnsInternal.CollectionChanged += ColumnsInternal_CollectionChanged;
 
             RowHeightEstimate = DATAGRID_defaultRowHeight;
             RowDetailsHeightEstimate = 0;
@@ -725,6 +728,8 @@ namespace Avalonia.Controls
             CurrentCellCoordinates = new DataGridCellCoordinates(-1, -1);
 
             RowGroupHeaderHeightEstimate = DATAGRID_defaultRowHeight;
+
+            UpdatePseudoClasses();
         }
 
         private void SetValueNoCallback<T>(AvaloniaProperty<T> property, T value, BindingPriority priority = BindingPriority.LocalValue)
@@ -849,9 +854,27 @@ namespace Avalonia.Controls
                 // can be set when the DataGrid is not part of the visual tree
                 _measured = false;
                 InvalidateMeasure();
+
+                UpdatePseudoClasses();
             }
         }
 
+        private void ColumnsInternal_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
+        {
+            if (e.Action == NotifyCollectionChangedAction.Add
+                || e.Action == NotifyCollectionChangedAction.Remove
+                || e.Action == NotifyCollectionChangedAction.Reset)
+            {
+                UpdatePseudoClasses();
+            }
+        }
+
+        internal void UpdatePseudoClasses()
+        {
+            PseudoClasses.Set(":empty-columns", !ColumnsInternal.GetVisibleColumns().Any());
+            PseudoClasses.Set(":empty-rows", !DataConnection.Any());
+        }
+
         private void OnSelectedIndexChanged(AvaloniaPropertyChangedEventArgs e)
         {
             if (!_areHandlersSuspended)
@@ -1346,7 +1369,6 @@ namespace Avalonia.Controls
         internal DataGridColumnCollection ColumnsInternal
         {
             get;
-            private set;
         }
 
         internal int AnchorSlot

src/Avalonia.Controls.DataGrid/DataGridCell.cs

@@ -3,6 +3,7 @@
 // Please see http://go.microsoft.com/fwlink/?LinkID=131993 for details.
 // All other rights reserved.
 
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Shapes;
 using Avalonia.Input;
@@ -12,6 +13,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// Represents an individual <see cref="T:Avalonia.Controls.DataGrid" /> cell.
     /// </summary>
+    [PseudoClasses(":selected", ":current", ":edited", ":invalid")]
     public class DataGridCell : ContentControl
     {
         private const string DATAGRIDCELL_elementRightGridLine = "PART_RightGridLine";

src/Avalonia.Controls.DataGrid/DataGridCheckBoxColumn.cs

@@ -17,9 +17,7 @@ namespace Avalonia.Controls
     /// </summary>
     public class DataGridCheckBoxColumn : DataGridBoundColumn
     {
-
         private bool _beganEditWithKeyboard;
-        private bool _isThreeState;
         private CheckBox _currentCheckBox;
         private DataGrid _owningGrid;
 
@@ -31,6 +29,12 @@ namespace Avalonia.Controls
             BindingTarget = CheckBox.IsCheckedProperty;
         }
 
+        /// <summary>
+        /// Defines the <see cref="IsThreeState"/> property.
+        /// </summary>
+        public static StyledProperty<bool> IsThreeStateProperty =
+            CheckBox.IsThreeStateProperty.AddOwner<DataGridCheckBoxColumn>();
+
         /// <summary>
         /// Gets or sets a value that indicates whether the hosted <see cref="T:System.Windows.Controls.CheckBox" /> controls allow three states or two. 
         /// </summary>
@@ -39,17 +43,17 @@ namespace Avalonia.Controls
         /// </returns>
         public bool IsThreeState
         {
-            get
+            get => GetValue(IsThreeStateProperty);
-            {
+            set => SetValue(IsThreeStateProperty, value);
-                return _isThreeState;
+        }
-            }
+
-            set
+        protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> change)
+        {
+            base.OnPropertyChanged(change);
+
+            if (change.Property == IsThreeStateProperty)
             {
-                if (_isThreeState != value)
+                NotifyPropertyChanged(change.Property.Name);
-                {
-                    _isThreeState = value;
-                    NotifyPropertyChanged(nameof(IsThreeState));
-                }
             }
         }
 
@@ -203,9 +207,9 @@ namespace Avalonia.Controls
             {
                 throw new ArgumentNullException("element");
             }
-            if(element is CheckBox checkBox)
+            if (element is CheckBox checkBox)
             {
-                checkBox.IsThreeState = IsThreeState;
+                DataGridHelper.SyncColumnProperty(this, checkBox, IsThreeStateProperty);
             }
             else
             {
@@ -229,7 +233,7 @@ namespace Avalonia.Controls
         {
             checkBox.HorizontalAlignment = HorizontalAlignment.Center;
             checkBox.VerticalAlignment = VerticalAlignment.Center;
-            checkBox.IsThreeState = IsThreeState;
+            DataGridHelper.SyncColumnProperty(this, checkBox, IsThreeStateProperty);
         }
 
         private bool EnsureOwningGrid()

src/Avalonia.Controls.DataGrid/DataGridColumn.cs

@@ -665,6 +665,7 @@ namespace Avalonia.Controls
         /// <param name="dataItem">
         /// The data item represented by the row that contains the intended cell.
         /// </param>
+        /// <param name="binding">When the method returns, contains the applied binding.</param>
         /// <returns>
         /// A new editing element that is bound to the column's <see cref="P:Avalonia.Controls.DataGridBoundColumn.Binding" /> property value.
         /// </returns>

src/Avalonia.Controls.DataGrid/DataGridColumnHeader.cs

@@ -14,12 +14,14 @@ using Avalonia.Utilities;
 using System;
 using Avalonia.Controls.Utils;
 using Avalonia.Controls.Mixins;
+using Avalonia.Controls.Metadata;
 
 namespace Avalonia.Controls
 {
     /// <summary>
     /// Represents an individual <see cref="T:Avalonia.Controls.DataGrid" /> column header.
     /// </summary>
+    [PseudoClasses(":dragIndicator", ":pressed", ":sortascending", ":sortdescending")]
     public class DataGridColumnHeader : ContentControl
     {
         private enum DragMode
@@ -338,8 +340,6 @@ namespace Avalonia.Controls
 
             if (OwningGrid != null && OwningGrid.ColumnHeaders != null)
             {
-                args.Pointer.Capture(this);
-
                 _dragMode = DragMode.MouseDown;
                 _frozenColumnsWidth = OwningGrid.ColumnsInternal.GetVisibleFrozenEdgedColumnsWidth();
                 _lastMousePositionHeaders = this.Translate(OwningGrid.ColumnHeaders, mousePosition);
@@ -411,8 +411,9 @@ namespace Avalonia.Controls
         }
 
         //TODO DragEvents
-        internal void OnMouseMove(ref bool handled, Point mousePosition, Point mousePositionHeaders)
+        internal void OnMouseMove(PointerEventArgs args, Point mousePosition, Point mousePositionHeaders)
         {
+            var handled = args.Handled;
             if (handled || OwningGrid == null || OwningGrid.ColumnHeaders == null)
             {
                 return;
@@ -436,7 +437,10 @@ namespace Avalonia.Controls
             }
 
             _lastMousePositionHeaders = mousePositionHeaders;
-
+            
+            if (args.Pointer.Captured != this && _dragMode == DragMode.Drag)
+                args.Pointer.Capture(this);
+            
             SetDragCursor(mousePosition);
         }
 
@@ -504,8 +508,7 @@ namespace Avalonia.Controls
             Point mousePosition = e.GetPosition(this);
             Point mousePositionHeaders = e.GetPosition(OwningGrid.ColumnHeaders);
 
-            bool handled = false;
+            OnMouseMove(e, mousePosition, mousePositionHeaders);
-            OnMouseMove(ref handled, mousePosition, mousePositionHeaders);
         }
 
         /// <summary>

src/Avalonia.Controls.DataGrid/DataGridDataConnection.cs

@@ -77,24 +77,7 @@ namespace Avalonia.Controls
             private set;
         }
 
-        public int Count
+        public int Count => GetCount(true);
-        {
-            get
-            {
-                IList list = List;
-                if (list != null)
-                {
-                    return list.Count;
-                }
-
-                if(DataSource is DataGridCollectionView cv)
-                {
-                    return cv.Count;
-                }
-
-                return DataSource?.Cast<object>().Count() ?? 0;
-            }
-        }
 
         public bool DataIsPrimitive
         {
@@ -210,6 +193,24 @@ namespace Avalonia.Controls
             }
         }
 
+        internal bool Any()
+        {
+            return GetCount(false) > 0;
+        }
+
+        /// <param name="allowSlow">When "allowSlow" is false, method will not use Linq.Count() method and will return 0 or 1 instead.</param>
+        private int GetCount(bool allowSlow)
+        {
+            return DataSource switch
+            {
+                ICollection collection => collection.Count,
+                DataGridCollectionView cv => cv.Count,
+                IEnumerable enumerable when allowSlow => enumerable.Cast<object>().Count(),
+                IEnumerable enumerable when !allowSlow => enumerable.Cast<object>().Any() ? 1 : 0,
+                _ => 0
+            };
+        }
+
         /// <summary>
         /// Puts the entity into editing mode if possible
         /// </summary>
@@ -675,6 +676,8 @@ namespace Avalonia.Controls
                     }
                     break;
             }
+
+            _owner.UpdatePseudoClasses();
         }
 
         private void UpdateDataProperties()

src/Avalonia.Controls.DataGrid/DataGridRow.cs

@@ -3,6 +3,7 @@
 // Please see http://go.microsoft.com/fwlink/?LinkID=131993 for details.
 // All other rights reserved.
 
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Shapes;
 using Avalonia.Controls.Templates;
@@ -20,6 +21,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// Represents a <see cref="T:Avalonia.Controls.DataGrid" /> row.
     /// </summary>
+    [PseudoClasses(":selected", ":editing", ":invalid")]
     public class DataGridRow : TemplatedControl
     {
 

src/Avalonia.Controls.DataGrid/DataGridRowGroupHeader.cs

@@ -3,6 +3,7 @@
 // Please see http://go.microsoft.com/fwlink/?LinkID=131993 for details.
 // All other rights reserved.
 
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Mixins;
 using Avalonia.Controls.Primitives;
 using Avalonia.Input;
@@ -13,6 +14,7 @@ using System.Reactive.Linq;
 
 namespace Avalonia.Controls
 {
+    [PseudoClasses(":pressed", ":current", ":expanded")]
     public class DataGridRowGroupHeader : TemplatedControl
     {
         private const string DATAGRIDROWGROUPHEADER_expanderButton = "ExpanderButton";

src/Avalonia.Controls.DataGrid/DataGridRowHeader.cs

@@ -3,6 +3,7 @@
 // Please see http://go.microsoft.com/fwlink/?LinkID=131993 for details.
 // All other rights reserved.
 
+using Avalonia.Controls.Metadata;
 using Avalonia.Input;
 using Avalonia.Media;
 using System.Diagnostics;
@@ -12,6 +13,7 @@ namespace Avalonia.Controls.Primitives
     /// <summary>
     /// Represents an individual <see cref="T:Avalonia.Controls.DataGrid" /> row header. 
     /// </summary>
+    [PseudoClasses(":invalid", ":selected", ":editing", ":current")]
     public class DataGridRowHeader : ContentControl
     {
         private const string DATAGRIDROWHEADER_elementRootName = "PART_Root";

src/Avalonia.Controls.DataGrid/DataGridTextColumn.cs

@@ -20,11 +20,6 @@ namespace Avalonia.Controls
     {
         private const string DATAGRID_TextColumnCellTextBlockMarginKey = "DataGridTextColumnCellTextBlockMargin";
 
-        private double? _fontSize;
-        private FontStyle? _fontStyle;
-        private FontWeight? _fontWeight;
-        private IBrush _foreground;
-
         /// <summary>
         /// Initializes a new instance of the <see cref="T:Avalonia.Controls.DataGridTextColumn" /> class.
         /// </summary>
@@ -36,18 +31,24 @@ namespace Avalonia.Controls
         /// <summary>
         /// Identifies the FontFamily dependency property.
         /// </summary>
-        public static readonly StyledProperty<string> FontFamilyProperty =
+        public static readonly AttachedProperty<FontFamily> FontFamilyProperty =
-            AvaloniaProperty.Register<DataGridTextColumn, string>(nameof(FontFamily));
+            TextBlock.FontFamilyProperty.AddOwner<DataGridTextColumn>();
 
         /// <summary>
         /// Gets or sets the font name.
         /// </summary>
-        public string FontFamily
+        public FontFamily FontFamily
         {
-            get { return GetValue(FontFamilyProperty); }
+            get => GetValue(FontFamilyProperty);
-            set { SetValue(FontFamilyProperty, value); }
+            set => SetValue(FontFamilyProperty, value);
         }
 
+        /// <summary>
+        /// Identifies the FontSize dependency property.
+        /// </summary>
+        public static readonly AttachedProperty<double> FontSizeProperty =
+            TextBlock.FontSizeProperty.AddOwner<DataGridTextColumn>();
+
         /// <summary>
         /// Gets or sets the font size.
         /// </summary>
@@ -55,74 +56,66 @@ namespace Avalonia.Controls
         [DefaultValue(double.NaN)]
         public double FontSize
         {
-            get
+            get => GetValue(FontSizeProperty);
-            {
+            set => SetValue(FontSizeProperty, value);
-                return _fontSize ?? Double.NaN;
-            }
-            set
-            {
-                if (_fontSize != value)
-                {
-                    _fontSize = value;
-                    NotifyPropertyChanged(nameof(FontSize));
-                }
-            }
         }
 
+        /// <summary>
+        /// Identifies the FontStyle dependency property.
+        /// </summary>
+        public static readonly AttachedProperty<FontStyle> FontStyleProperty =
+            TextBlock.FontStyleProperty.AddOwner<DataGridTextColumn>();
+
         /// <summary>
         /// Gets or sets the font style.
         /// </summary>
         public FontStyle FontStyle
         {
-            get
+            get => GetValue(FontStyleProperty);
-            {
+            set => SetValue(FontStyleProperty, value);
-                return _fontStyle ?? FontStyle.Normal;
-            }
-            set
-            {
-                if (_fontStyle != value)
-                {
-                    _fontStyle = value;
-                    NotifyPropertyChanged(nameof(FontStyle));
-                }
-            }
         }
 
+        /// <summary>
+        /// Identifies the FontWeight dependency property.
+        /// </summary>
+        public static readonly AttachedProperty<FontWeight> FontWeightProperty =
+            TextBlock.FontWeightProperty.AddOwner<DataGridTextColumn>();
+
         /// <summary>
         /// Gets or sets the font weight or thickness.
         /// </summary>
         public FontWeight FontWeight
         {
-            get
+            get => GetValue(FontWeightProperty);
-            {
+            set => SetValue(FontWeightProperty, value);
-                return _fontWeight ?? FontWeight.Normal;
-            }
-            set
-            {
-                if (_fontWeight != value)
-                {
-                    _fontWeight = value;
-                    NotifyPropertyChanged(nameof(FontWeight));
-                }
-            }
         }
 
+        /// <summary>
+        /// Identifies the Foreground dependency property.
+        /// </summary>
+        public static readonly AttachedProperty<IBrush> ForegroundProperty =
+            TextBlock.ForegroundProperty.AddOwner<DataGridTextColumn>();
+
         /// <summary>
         /// Gets or sets a brush that describes the foreground of the column cells.
         /// </summary>
         public IBrush Foreground
         {
-            get
+            get => GetValue(ForegroundProperty);
-            {
+            set => SetValue(ForegroundProperty, value);
-                return _foreground;
+        }
-            }
+
-            set
+        protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> change)
+        {
+            base.OnPropertyChanged(change);
+
+            if (change.Property == FontFamilyProperty
+                || change.Property == FontSizeProperty
+                || change.Property == FontStyleProperty
+                || change.Property == FontWeightProperty
+                || change.Property == ForegroundProperty)
             {
-                if (_foreground != value)
+                NotifyPropertyChanged(change.Property.Name);
-                {
-                    _foreground = value;
-                    NotifyPropertyChanged(nameof(Foreground));
-                }
             }
         }
 
@@ -154,26 +147,7 @@ namespace Avalonia.Controls
                 Background = new SolidColorBrush(Colors.Transparent)
             };
 
-            if (IsSet(FontFamilyProperty))
+            SyncProperties(textBox);
-            {
-                textBox.FontFamily = FontFamily;
-            }
-            if (_fontSize.HasValue)
-            {
-                textBox.FontSize = _fontSize.Value;
-            }
-            if (_fontStyle.HasValue)
-            {
-                textBox.FontStyle = _fontStyle.Value;
-            }
-            if (_fontWeight.HasValue)
-            {
-                textBox.FontWeight = _fontWeight.Value;
-            }
-            if (_foreground != null)
-            {
-                textBox.Foreground = _foreground;
-            }
 
             return textBox;
         }
@@ -192,26 +166,8 @@ namespace Avalonia.Controls
                 VerticalAlignment = VerticalAlignment.Center
             };
 
-            if (IsSet(FontFamilyProperty))
+            SyncProperties(textBlockElement);
-            {
+
-                textBlockElement.FontFamily = FontFamily;
-            }
-            if (_fontSize.HasValue)
-            {
-                textBlockElement.FontSize = _fontSize.Value;
-            }
-            if (_fontStyle.HasValue)
-            {
-                textBlockElement.FontStyle = _fontStyle.Value;
-            }
-            if (_fontWeight.HasValue)
-            {
-                textBlockElement.FontWeight = _fontWeight.Value;
-            }
-            if (_foreground != null)
-            {
-                textBlockElement.Foreground = _foreground;
-            }
             if (Binding != null)
             {
                 textBlockElement.Bind(TextBlock.TextProperty, Binding);
@@ -261,99 +217,42 @@ namespace Avalonia.Controls
                 throw new ArgumentNullException("element");
             }
 
-            if(element is TextBox textBox)
+            if (element is AvaloniaObject content)
             {
                 if (propertyName == nameof(FontFamily))
                 {
-                    textBox.FontFamily = FontFamily;
+                    DataGridHelper.SyncColumnProperty(this, content, FontFamilyProperty);
                 }
                 else if (propertyName == nameof(FontSize))
                 {
-                    SetTextFontSize(textBox, TextBox.FontSizeProperty);
+                    DataGridHelper.SyncColumnProperty(this, content, FontSizeProperty);
                 }
                 else if (propertyName == nameof(FontStyle))
                 {
-                    textBox.FontStyle = FontStyle;
+                    DataGridHelper.SyncColumnProperty(this, content, FontStyleProperty);
                 }
                 else if (propertyName == nameof(FontWeight))
                 {
-                    textBox.FontWeight = FontWeight;
+                    DataGridHelper.SyncColumnProperty(this, content, FontWeightProperty);
                 }
                 else if (propertyName == nameof(Foreground))
                 {
-                    textBox.Foreground = Foreground;
+                    DataGridHelper.SyncColumnProperty(this, content, ForegroundProperty);
-                }
-                else
-                {
-                    if (FontFamily != null)
-                    {
-                        textBox.FontFamily = FontFamily;
-                    }
-                    SetTextFontSize(textBox, TextBox.FontSizeProperty);
-                    textBox.FontStyle = FontStyle;
-                    textBox.FontWeight = FontWeight;
-                    if (Foreground != null)
-                    {
-                        textBox.Foreground = Foreground;
-                    }
-                }
-
-            }
-            else if (element is TextBlock textBlock)
-            {
-                if (propertyName == nameof(FontFamily))
-                {
-                    textBlock.FontFamily = FontFamily;
-                }
-                else if (propertyName == nameof(FontSize))
-                {
-                    SetTextFontSize(textBlock, TextBlock.FontSizeProperty);
-                }
-                else if (propertyName == nameof(FontStyle))
-                {
-                    textBlock.FontStyle = FontStyle;
-                }
-                else if (propertyName == nameof(FontWeight))
-                {
-                    textBlock.FontWeight = FontWeight;
-                }
-                else if (propertyName == nameof(Foreground))
-                {
-                    textBlock.Foreground = Foreground;
-                }
-                else
-                {
-                    if (FontFamily != null)
-                    {
-                        textBlock.FontFamily = FontFamily;
-                    }
-                    SetTextFontSize(textBlock, TextBlock.FontSizeProperty);
-                    textBlock.FontStyle = FontStyle;
-                    textBlock.FontWeight = FontWeight;
-                    if (Foreground != null)
-                    {
-                        textBlock.Foreground = Foreground;
-                    }
                 }
             }
             else
             {
-                throw DataGridError.DataGrid.ValueIsNotAnInstanceOfEitherOr("element", typeof(TextBox), typeof(TextBlock));
+                throw DataGridError.DataGrid.ValueIsNotAnInstanceOf("element", typeof(AvaloniaObject));
             }
         }
 
-        private void SetTextFontSize(AvaloniaObject textElement, AvaloniaProperty fontSizeProperty)
+        private void SyncProperties(AvaloniaObject content)
         {
-            double newFontSize = FontSize;
+            DataGridHelper.SyncColumnProperty(this, content, FontFamilyProperty);
-            if (double.IsNaN(newFontSize))
+            DataGridHelper.SyncColumnProperty(this, content, FontSizeProperty);
-            {
+            DataGridHelper.SyncColumnProperty(this, content, FontStyleProperty);
-                textElement.ClearValue(fontSizeProperty);
+            DataGridHelper.SyncColumnProperty(this, content, FontWeightProperty);
-            }
+            DataGridHelper.SyncColumnProperty(this, content, ForegroundProperty);
-            else
-            {
-                textElement.SetValue(fontSizeProperty, newFontSize);
-            }
         }
-
     }
 }

src/Avalonia.Controls.DataGrid/Properties/AssemblyInfo.cs

@@ -1,10 +1,13 @@
 using System.Reflection;
 using System.Runtime.CompilerServices;
 using Avalonia.Metadata;
-
+#if SIGNED_BUILD
+[assembly: InternalsVisibleTo("Avalonia.Controls.DataGrid.UnitTests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c1bba1142285fe0419326fb25866ba62c47e6c2b5c1ab0c95b46413fad375471232cb81706932e1cef38781b9ebd39d5100401bacb651c6c5bbf59e571e81b3bc08d2a622004e08b1a6ece82a7e0b9857525c86d2b95fab4bc3dce148558d7f3ae61aa3a234086902aeface87d9dfdd32b9d2fe3c6dd4055b5ab4b104998bd87")]
+[assembly: InternalsVisibleTo("Avalonia.DesignerSupport, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c1bba1142285fe0419326fb25866ba62c47e6c2b5c1ab0c95b46413fad375471232cb81706932e1cef38781b9ebd39d5100401bacb651c6c5bbf59e571e81b3bc08d2a622004e08b1a6ece82a7e0b9857525c86d2b95fab4bc3dce148558d7f3ae61aa3a234086902aeface87d9dfdd32b9d2fe3c6dd4055b5ab4b104998bd87")]
+#else
 [assembly: InternalsVisibleTo("Avalonia.Controls.DataGrid.UnitTests")]
 [assembly: InternalsVisibleTo("Avalonia.DesignerSupport")]
-
+#endif
 [assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Controls")]
 [assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Controls.Collections")]
 [assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Controls.Primitives")]

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

@@ -588,18 +588,11 @@
             <!--<DataGridColumnHeader Name="PART_TopRightCornerHeader"
                                   Grid.Column="2"
                                   Template="{StaticResource TopRightHeaderTemplate}" />-->
-            <!--<Rectangle Name="PART_ColumnHeadersAndRowsSeparator"
+            <Rectangle Name="PART_ColumnHeadersAndRowsSeparator"
                        Grid.ColumnSpan="3"
                        VerticalAlignment="Bottom"
-                       StrokeThickness="1"
                        Height="1"
-                       Fill="{DynamicResource DataGridGridLinesBrush}" />-->
+                       Fill="{DynamicResource DataGridGridLinesBrush}" />
-            <Border Name="PART_ColumnHeadersAndRowsSeparator"
-                    Grid.ColumnSpan="3"
-                    Height="2"
-                    VerticalAlignment="Bottom"
-                    BorderThickness="0,0,0,1"
-                    BorderBrush="{DynamicResource DataGridGridLinesBrush}" />
 
             <DataGridRowsPresenter Name="PART_RowsPresenter"
                                    Grid.Row="1"
@@ -642,4 +635,14 @@
       </ControlTemplate>
     </Setter>
   </Style>
+
+  <Style Selector="DataGrid:empty-columns /template/ DataGridColumnHeader#PART_TopLeftCornerHeader">
+    <Setter Property="IsVisible" Value="False" />
+  </Style>
+  <Style Selector="DataGrid:empty-columns /template/ DataGridColumnHeadersPresenter#PART_ColumnHeadersPresenter">
+    <Setter Property="IsVisible" Value="False" />
+  </Style>
+  <Style Selector="DataGrid:empty-columns /template/ Rectangle#PART_ColumnHeadersAndRowsSeparator">
+    <Setter Property="IsVisible" Value="False" />
+  </Style>
 </Styles>

src/Avalonia.Controls.DataGrid/Utils/DataGridHelper.cs

@@ -0,0 +1,22 @@
+namespace Avalonia.Controls
+{
+    internal static class DataGridHelper
+    {
+        internal static void SyncColumnProperty<T>(AvaloniaObject column, AvaloniaObject content, AvaloniaProperty<T> property)
+        {
+            SyncColumnProperty(column, content, property, property);
+        }
+
+        internal static void SyncColumnProperty<T>(AvaloniaObject column, AvaloniaObject content, AvaloniaProperty<T> contentProperty, AvaloniaProperty<T> columnProperty)
+        {
+            if (!column.IsSet(columnProperty))
+            {
+                content.ClearValue(contentProperty);
+            }
+            else
+            {
+                content.SetValue(contentProperty, column.GetValue(columnProperty));
+            }
+        }
+    }
+}

src/Avalonia.Controls/ApiCompatBaseline.txt

@@ -8,6 +8,12 @@ MembersMustExist : Member 'public void Avalonia.Controls.ListBox.Selection.set(A
 TypesMustExist : Type 'Avalonia.Controls.SelectionModel' does not exist in the implementation but it does exist in the contract.
 TypesMustExist : Type 'Avalonia.Controls.SelectionModelChildrenRequestedEventArgs' does not exist in the implementation but it does exist in the contract.
 TypesMustExist : Type 'Avalonia.Controls.SelectionModelSelectionChangedEventArgs' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.StyledProperty<Avalonia.Controls.IControl> Avalonia.StyledProperty<Avalonia.Controls.IControl> Avalonia.Controls.SplitView.ContentProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.StyledProperty<Avalonia.Controls.IControl> Avalonia.StyledProperty<Avalonia.Controls.IControl> Avalonia.Controls.SplitView.PaneProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.Controls.IControl Avalonia.Controls.SplitView.Content.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public void Avalonia.Controls.SplitView.Content.set(Avalonia.Controls.IControl)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.Controls.IControl Avalonia.Controls.SplitView.Pane.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public void Avalonia.Controls.SplitView.Pane.set(Avalonia.Controls.IControl)' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'public Avalonia.DirectProperty<Avalonia.Controls.TreeView, Avalonia.Controls.ISelectionModel> Avalonia.DirectProperty<Avalonia.Controls.TreeView, Avalonia.Controls.ISelectionModel> Avalonia.Controls.TreeView.SelectionProperty' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'public Avalonia.Interactivity.RoutedEvent<Avalonia.Controls.SelectionChangedEventArgs> Avalonia.Interactivity.RoutedEvent<Avalonia.Controls.SelectionChangedEventArgs> Avalonia.Controls.TreeView.SelectionChangedEvent' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'public Avalonia.Controls.ISelectionModel Avalonia.Controls.TreeView.Selection.get()' does not exist in the implementation but it does exist in the contract.
@@ -17,4 +23,4 @@ InterfacesShouldHaveSameMembers : Interface member 'public System.String[] Avalo
 MembersMustExist : Member 'public Avalonia.DirectProperty<Avalonia.Controls.Primitives.SelectingItemsControl, Avalonia.Controls.ISelectionModel> Avalonia.DirectProperty<Avalonia.Controls.Primitives.SelectingItemsControl, Avalonia.Controls.ISelectionModel> Avalonia.Controls.Primitives.SelectingItemsControl.SelectionProperty' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'protected Avalonia.Controls.ISelectionModel Avalonia.Controls.Primitives.SelectingItemsControl.Selection.get()' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'protected void Avalonia.Controls.Primitives.SelectingItemsControl.Selection.set(Avalonia.Controls.ISelectionModel)' does not exist in the implementation but it does exist in the contract.
-Total Issues: 18
+Total Issues: 24

src/Avalonia.Controls/AutoCompleteBox.cs

@@ -14,6 +14,7 @@ using System.Reactive.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using Avalonia.Collections;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
 using Avalonia.Controls.Utils;
@@ -30,6 +31,7 @@ namespace Avalonia.Controls
     /// <see cref="E:Avalonia.Controls.AutoCompleteBox.Populated" />
     /// event.
     /// </summary>
+    [PseudoClasses(":dropdownopen")]
     public class PopulatedEventArgs : EventArgs
     {
         /// <summary>
@@ -225,6 +227,27 @@ namespace Avalonia.Controls
         Custom = 13,
     }
 
+    /// <summary>
+    /// Represents the selector used by the
+    /// <see cref="T:Avalonia.Controls.AutoCompleteBox" /> control to
+    /// determine how the specified text should be modified with an item.
+    /// </summary>
+    /// <returns>
+    /// Modified text that will be used by the
+    /// <see cref="T:Avalonia.Controls.AutoCompleteBox" />.
+    /// </returns>
+    /// <param name="search">The string used as the basis for filtering.</param>
+    /// <param name="item">
+    /// The selected item that should be combined with the
+    /// <paramref name="search" /> parameter.
+    /// </param>
+    /// <typeparam name="T">
+    /// The type used for filtering the
+    /// <see cref="T:Avalonia.Controls.AutoCompleteBox" />.
+    /// This type can be either a string or an object.
+    /// </typeparam>
+    public delegate string AutoCompleteSelector<T>(string search, T item);
+
     /// <summary>
     /// Represents a control that provides a text box for user input and a
     /// drop-down that contains possible matches based on the input in the text
@@ -362,6 +385,9 @@ namespace Avalonia.Controls
         private AutoCompleteFilterPredicate<object> _itemFilter;
         private AutoCompleteFilterPredicate<string> _textFilter = AutoCompleteSearch.GetFilter(AutoCompleteFilterMode.StartsWith);
 
+        private AutoCompleteSelector<object> _itemSelector;
+        private AutoCompleteSelector<string> _textSelector;
+
         public static readonly RoutedEvent<SelectionChangedEventArgs> SelectionChangedEvent =
             RoutedEvent.Register<SelectionChangedEventArgs>(nameof(SelectionChanged), RoutingStrategies.Bubble, typeof(AutoCompleteBox));
 
@@ -528,6 +554,34 @@ namespace Avalonia.Controls
                 (o, v) => o.TextFilter = v,
                 unsetValue: AutoCompleteSearch.GetFilter(AutoCompleteFilterMode.StartsWith));
 
+        /// <summary>
+        /// Identifies the
+        /// <see cref="P:Avalonia.Controls.AutoCompleteBox.ItemSelector" />
+        /// dependency property.
+        /// </summary>
+        /// <value>The identifier for the
+        /// <see cref="P:Avalonia.Controls.AutoCompleteBox.ItemSelector" />
+        /// dependency property.</value>
+        public static readonly DirectProperty<AutoCompleteBox, AutoCompleteSelector<object>> ItemSelectorProperty =
+            AvaloniaProperty.RegisterDirect<AutoCompleteBox, AutoCompleteSelector<object>>(
+                nameof(ItemSelector),
+                o => o.ItemSelector,
+                (o, v) => o.ItemSelector = v);
+
+        /// <summary>
+        /// Identifies the
+        /// <see cref="P:Avalonia.Controls.AutoCompleteBox.TextSelector" />
+        /// dependency property.
+        /// </summary>
+        /// <value>The identifier for the
+        /// <see cref="P:Avalonia.Controls.AutoCompleteBox.TextSelector" />
+        /// dependency property.</value>
+        public static readonly DirectProperty<AutoCompleteBox, AutoCompleteSelector<string>> TextSelectorProperty =
+            AvaloniaProperty.RegisterDirect<AutoCompleteBox, AutoCompleteSelector<string>>(
+                nameof(TextSelector),
+                o => o.TextSelector,
+                (o, v) => o.TextSelector = v);
+
         /// <summary>
         /// Identifies the
         /// <see cref="P:Avalonia.Controls.AutoCompleteBox.ItemsSource" />
@@ -1061,6 +1115,40 @@ namespace Avalonia.Controls
             set { SetAndRaise(TextFilterProperty, ref _textFilter, value); }
         }
 
+        /// <summary>
+        /// Gets or sets the custom method that combines the user-entered
+        /// text and one of the items specified by the
+        /// <see cref="P:Avalonia.Controls.AutoCompleteBox.ItemsSource" />.
+        /// </summary>
+        /// <value>
+        /// The custom method that combines the user-entered
+        /// text and one of the items specified by the
+        /// <see cref="P:Avalonia.Controls.AutoCompleteBox.ItemsSource" />.
+        /// </value>
+        public AutoCompleteSelector<object> ItemSelector
+        {
+            get { return _itemSelector; }
+            set { SetAndRaise(ItemSelectorProperty, ref _itemSelector, value); }
+        }
+
+        /// <summary>
+        /// Gets or sets the custom method that combines the user-entered
+        /// text and one of the items specified by the
+        /// <see cref="P:Avalonia.Controls.AutoCompleteBox.ItemsSource" />
+        /// in a text-based way.
+        /// </summary>
+        /// <value>
+        /// The custom method that combines the user-entered
+        /// text and one of the items specified by the
+        /// <see cref="P:Avalonia.Controls.AutoCompleteBox.ItemsSource" />
+        /// in a text-based way.
+        /// </value>
+        public AutoCompleteSelector<string> TextSelector
+        {
+            get { return _textSelector; }
+            set { SetAndRaise(TextSelectorProperty, ref _textSelector, value); }
+        }
+
         public Func<string, CancellationToken, Task<IEnumerable<object>>> AsyncPopulator
         {
             get { return _asyncPopulator; }
@@ -2329,6 +2417,14 @@ namespace Avalonia.Controls
             {
                 text = SearchText;
             }
+            else if (TextSelector != null)
+            {
+                text = TextSelector(SearchText, FormatValue(newItem, true));
+            }
+            else if (ItemSelector != null)
+            {
+                text = ItemSelector(SearchText, newItem);
+            }
             else
             {
                 text = FormatValue(newItem, true);

src/Avalonia.Controls/Button.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Linq;
 using System.Windows.Input;
+using Avalonia.Controls.Metadata;
 using Avalonia.Data;
 using Avalonia.Input;
 using Avalonia.Interactivity;
@@ -28,6 +29,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// A button control.
     /// </summary>
+    [PseudoClasses(":pressed")]
     public class Button : ContentControl
     {
         /// <summary>

src/Avalonia.Controls/ButtonSpinner.cs

@@ -1,4 +1,5 @@
 using System;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Data;
 using Avalonia.Input;
@@ -15,6 +16,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// Represents a spinner control that includes two Buttons.
     /// </summary>
+    [PseudoClasses(":left", ":right")]
     public class ButtonSpinner : Spinner
     {
         /// <summary>

src/Avalonia.Controls/Calendar/CalendarButton.cs

@@ -3,6 +3,7 @@
 // Please see http://go.microsoft.com/fwlink/?LinkID=131993 for details.
 // All other rights reserved.
 
+using Avalonia.Controls.Metadata;
 using Avalonia.Input;
 using System;
 
@@ -12,6 +13,7 @@ namespace Avalonia.Controls.Primitives
     /// Represents a button on a
     /// <see cref="T:Avalonia.Controls.Calendar" />.
     /// </summary>
+    [PseudoClasses(":selected", ":inactive", ":btnfocused")]
     public sealed class CalendarButton : Button
     {
         /// <summary>

src/Avalonia.Controls/Calendar/CalendarDatePicker.cs

@@ -420,7 +420,7 @@ namespace Avalonia.Controls
                 _calendar.DayButtonMouseUp -= Calendar_DayButtonMouseUp;
                 _calendar.DisplayDateChanged -= Calendar_DisplayDateChanged;
                 _calendar.SelectedDatesChanged -= Calendar_SelectedDatesChanged;
-                _calendar.PointerPressed -= Calendar_PointerPressed;
+                _calendar.PointerReleased -= Calendar_PointerReleased;
                 _calendar.KeyDown -= Calendar_KeyDown;
             }
             _calendar = e.NameScope.Find<Calendar>(ElementCalendar);
@@ -435,7 +435,7 @@ namespace Avalonia.Controls
                 _calendar.DayButtonMouseUp += Calendar_DayButtonMouseUp;
                 _calendar.DisplayDateChanged += Calendar_DisplayDateChanged;
                 _calendar.SelectedDatesChanged += Calendar_SelectedDatesChanged;
-                _calendar.PointerPressed += Calendar_PointerPressed;
+                _calendar.PointerReleased += Calendar_PointerReleased;
                 _calendar.KeyDown += Calendar_KeyDown;
                 //_calendar.SizeChanged += new SizeChangedEventHandler(Calendar_SizeChanged);
                 //_calendar.IsTabStop = true;
@@ -831,9 +831,10 @@ namespace Avalonia.Controls
                 }
             }
         }
-        private void Calendar_PointerPressed(object sender, PointerPressedEventArgs e)
+        private void Calendar_PointerReleased(object sender, PointerReleasedEventArgs e)
         {
-            if (e.GetCurrentPoint(this).Properties.IsLeftButtonPressed)
+             
+            if (e.InitialPressMouseButton == MouseButton.Left)
             {
                 e.Handled = true;
             }

src/Avalonia.Controls/Calendar/CalendarDayButton.cs

@@ -5,10 +5,12 @@
 
 using System;
 using System.Globalization;
+using Avalonia.Controls.Metadata;
 using Avalonia.Input;
 
 namespace Avalonia.Controls.Primitives
 {
+    [PseudoClasses(":pressed", ":disabled", ":selected", ":inactive", ":today", ":blackout", ":dayfocused")]
     public sealed class CalendarDayButton : Button
     {
         /// <summary>

src/Avalonia.Controls/Calendar/CalendarItem.cs

@@ -7,6 +7,7 @@ using System;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Globalization;
+using Avalonia.Controls.Metadata;
 using Avalonia.Data;
 using Avalonia.Input;
 using Avalonia.Interactivity;
@@ -18,6 +19,7 @@ namespace Avalonia.Controls.Primitives
     /// Represents the currently displayed month or year on a
     /// <see cref="T:Avalonia.Controls.Calendar" />.
     /// </summary>
+    [PseudoClasses(":calendardisabled")]
     public sealed class CalendarItem : TemplatedControl
     {
         /// <summary>
@@ -34,11 +36,7 @@ namespace Avalonia.Controls.Primitives
         private Button _headerButton;
         private Button _nextButton;
         private Button _previousButton;
-        private Grid _monthView;
-        private Grid _yearView;
         private ITemplate<IControl> _dayTitleTemplate;
-        private CalendarButton _lastCalendarButton;
-        private CalendarDayButton _lastCalendarDayButton;
         
         private DateTime _currentMonth;
         private bool _isMouseLeftButtonDown = false;
@@ -158,38 +156,12 @@ namespace Avalonia.Controls.Primitives
         /// <summary>
         /// Gets the Grid that hosts the content when in month mode.
         /// </summary>
-        internal Grid MonthView
+        internal Grid MonthView { get; set; }
-        {
-            get { return _monthView; }
-            private set
-            {
-                if (_monthView != null)
-                    _monthView.PointerLeave -= MonthView_MouseLeave;
-
-                _monthView = value;
-
-                if (_monthView != null)
-                    _monthView.PointerLeave += MonthView_MouseLeave;
-            }
-        }
         /// <summary>
         /// Gets the Grid that hosts the content when in year or decade mode.
         /// </summary>
-        internal Grid YearView
+        internal Grid YearView { get; set; }
-        {
+        
-            get { return _yearView; }
-            private set
-            {
-                if (_yearView != null)
-                    _yearView.PointerLeave -= YearView_MouseLeave;
-
-                _yearView = value;
-
-                if (_yearView != null)
-                    _yearView.PointerLeave += YearView_MouseLeave;
-            }
-        }
-
         private void PopulateGrids()
         {
             if (MonthView != null)
@@ -224,7 +196,6 @@ namespace Avalonia.Controls.Primitives
                         cell.CalendarDayButtonMouseDown += Cell_MouseLeftButtonDown;
                         cell.CalendarDayButtonMouseUp += Cell_MouseLeftButtonUp;
                         cell.PointerEnter += Cell_MouseEnter;
-                        cell.PointerLeave += Cell_MouseLeave;
                         cell.Click += Cell_Click;
                         children.Add(cell);
                     }
@@ -254,7 +225,6 @@ namespace Avalonia.Controls.Primitives
                         month.CalendarLeftMouseButtonDown += Month_CalendarButtonMouseDown;
                         month.CalendarLeftMouseButtonUp += Month_CalendarButtonMouseUp;
                         month.PointerEnter += Month_MouseEnter;
-                        month.PointerLeave += Month_MouseLeave;
                         children.Add(month);
                     }
                 }
@@ -935,17 +905,7 @@ namespace Avalonia.Controls.Primitives
                 }
             }
         }
-        internal void Cell_MouseLeave(object sender, PointerEventArgs e)
+        
-        {
-            if (_isMouseLeftButtonDown)
-            {
-                CalendarDayButton b = (CalendarDayButton)sender;
-                // The button is in Pressed state. Change the state to normal.
-                if (e.Pointer.Captured == b)
-                    e.Pointer.Capture(null);
-                _lastCalendarDayButton = b;
-            }
-        }
         internal void Cell_MouseLeftButtonDown(object sender, PointerPressedEventArgs e)
         {
             if (Owner != null)
@@ -1205,35 +1165,6 @@ namespace Avalonia.Controls.Primitives
             }
         }
 
-        private void Month_MouseLeave(object sender, PointerEventArgs e)
-        {
-            if (_isMouseLeftButtonDownYearView)
-            {
-                CalendarButton b = (CalendarButton)sender;
-                // The button is in Pressed state. Change the state to normal.
-                if (e.Pointer.Captured == b)
-                    e.Pointer.Capture(null);
-                //b.ReleaseMouseCapture();
-
-                _lastCalendarButton = b;
-            }
-        }
-        private void MonthView_MouseLeave(object sender, PointerEventArgs e)
-        {
-            if (_lastCalendarDayButton != null)
-            {
-                e.Pointer.Capture(_lastCalendarDayButton);
-            }
-        }
-
-        private void YearView_MouseLeave(object sender, PointerEventArgs e)
-        {
-            if (_lastCalendarButton != null)
-            {
-                e.Pointer.Capture(_lastCalendarButton);
-            }
-        }
-        
         internal void UpdateDisabled(bool isEnabled)
         {
             PseudoClasses.Set(":calendardisabled", !isEnabled);

src/Avalonia.Controls/Chrome/CaptionButtons.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Reactive.Disposables;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 
 #nullable enable
@@ -9,6 +10,7 @@ namespace Avalonia.Controls.Chrome
     /// <summary>
     /// Draws window minimize / maximize / close buttons in a <see cref="TitleBar"/> when managed client decorations are enabled.
     /// </summary>
+    [PseudoClasses(":minimized", ":normal", ":maximized", ":fullscreen")]
     public class CaptionButtons : TemplatedControl
     {
         private CompositeDisposable? _disposables;

src/Avalonia.Controls/Chrome/TitleBar.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Reactive.Disposables;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 
 #nullable enable
@@ -9,6 +10,7 @@ namespace Avalonia.Controls.Chrome
     /// <summary>
     /// Draws a titlebar when managed client decorations are enabled.
     /// </summary>
+    [PseudoClasses(":minimized", ":normal", ":maximized", ":fullscreen")]
     public class TitleBar : TemplatedControl
     {
         private CompositeDisposable? _disposables;

src/Avalonia.Controls/ComboBox.cs

@@ -257,7 +257,7 @@ namespace Avalonia.Controls
         }
 
         /// <inheritdoc/>
-        protected override void OnPointerPressed(PointerPressedEventArgs e)
+        protected override void OnPointerReleased(PointerReleasedEventArgs e)
         {
             if (!e.Handled)
             {
@@ -276,7 +276,7 @@ namespace Avalonia.Controls
                 }
             }
 
-            base.OnPointerPressed(e);
+            base.OnPointerReleased(e);
         }
 
         /// <inheritdoc/>

src/Avalonia.Controls/ContextMenu.cs

@@ -62,6 +62,12 @@ namespace Avalonia.Controls
         public static readonly StyledProperty<Rect?> PlacementRectProperty =
             AvaloniaProperty.Register<Popup, Rect?>(nameof(PlacementRect));
 
+        /// <summary>
+        /// Defines the <see cref="WindowManagerAddShadowHint"/> property.
+        /// </summary>
+        public static readonly StyledProperty<bool> WindowManagerAddShadowHintProperty  =
+            Popup.WindowManagerAddShadowHintProperty.AddOwner<ContextMenu>();
+
         /// <summary>
         /// Defines the <see cref="PlacementTarget"/> property.
         /// </summary>
@@ -158,6 +164,12 @@ namespace Avalonia.Controls
             set { SetValue(PlacementModeProperty, value); }
         }
 
+        public bool WindowManagerAddShadowHint
+        {
+            get { return GetValue(WindowManagerAddShadowHintProperty); }
+            set { SetValue(WindowManagerAddShadowHintProperty, value); }
+        }
+
         /// <summary>
         /// Gets or sets the the anchor rectangle within the parent that the context menu will be placed
         /// relative to when <see cref="PlacementMode"/> is <see cref="PlacementMode.AnchorAndGravity"/>.
@@ -267,6 +279,7 @@ namespace Avalonia.Controls
                     PlacementTarget = PlacementTarget ?? control,
                     IsLightDismissEnabled = true,
                     OverlayDismissEventPassThrough = true,
+                    WindowManagerAddShadowHint = WindowManagerAddShadowHint,
                 };
 
                 _popup.Opened += PopupOpened;

src/Avalonia.Controls/DataValidationErrors.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Reactive.Linq;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Templates;
 using Avalonia.Data;
 
@@ -14,6 +15,7 @@ namespace Avalonia.Controls
     /// <remarks>
     /// You will probably only want to create instances inside of control templates.
     /// </remarks>
+    [PseudoClasses(":error")]
     public class DataValidationErrors : ContentControl
     {
         /// <summary>

src/Avalonia.Controls/DateTimePickers/DatePicker.cs

@@ -1,4 +1,5 @@
-using Avalonia.Controls.Primitives;
+using Avalonia.Controls.Metadata;
+using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Shapes;
 using Avalonia.Controls.Templates;
 using Avalonia.Interactivity;
@@ -11,6 +12,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// A control to allow the user to select a date
     /// </summary>
+    [PseudoClasses(":hasnodate")]
     public class DatePicker : TemplatedControl
     {
         /// <summary>

src/Avalonia.Controls/DateTimePickers/DateTimePickerPanel.cs

@@ -486,9 +486,9 @@ namespace Avalonia.Controls.Primitives
             switch (panelType)
             {
                 case DateTimePickerPanelType.Year:
-                    return new DateTime(value, FormatDate.Month, FormatDate.Day).ToString(ItemFormat);
+                    return new DateTime(value, 1, 1).ToString(ItemFormat);
                 case DateTimePickerPanelType.Month:
-                    return new DateTime(FormatDate.Year, value, FormatDate.Day).ToString(ItemFormat);
+                    return new DateTime(FormatDate.Year, value, 1).ToString(ItemFormat);
                 case DateTimePickerPanelType.Day:
                     return new DateTime(FormatDate.Year, FormatDate.Month, value).ToString(ItemFormat);
                 case DateTimePickerPanelType.Hour:

src/Avalonia.Controls/DateTimePickers/TimePicker.cs

@@ -1,4 +1,5 @@
-using Avalonia.Controls.Primitives;
+using Avalonia.Controls.Metadata;
+using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Shapes;
 using Avalonia.Controls.Templates;
 using System;
@@ -9,6 +10,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// A control to allow the user to select a time
     /// </summary>
+    [PseudoClasses(":hasnotime")]
     public class TimePicker : TemplatedControl
     {
         /// <summary>

src/Avalonia.Controls/Expander.cs

@@ -1,6 +1,6 @@
 using Avalonia.Animation;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
-using Avalonia.Data;
 
 namespace Avalonia.Controls
 {
@@ -12,6 +12,7 @@ namespace Avalonia.Controls
         Right
     }
 
+    [PseudoClasses(":expanded", ":up", ":down", ":left", ":right")]
     public class Expander : HeaderedContentControl
     {
         public static readonly StyledProperty<IPageTransition> ContentTransitionProperty =

src/Avalonia.Controls/Generators/ItemContainerGenerator`1.cs

@@ -47,11 +47,7 @@ namespace Avalonia.Controls.Generators
         {
             var container = item as T;
 
-            if (item == null)
+            if (container != null)
-            {
-                return null;
-            }
-            else if (container != null)
             {
                 return container;
             }