Merge branch 'master' into fast-theme-switching-fluent-theme

packages/Avalonia/Avalonia.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-      <TargetFrameworks>netstandard2.0;net461;netcoreapp2.0;net6.0</TargetFrameworks>
+      <TargetFrameworks>net6.0;netstandard2.0;net461;netcoreapp2.0</TargetFrameworks>
       <PackageId>Avalonia</PackageId>
   </PropertyGroup>
 

readme.md

@@ -75,6 +75,12 @@ For more information see the [.NET Foundation Code of Conduct](https://dotnetfou
 
 Avalonia is licenced under the [MIT licence](licence.md).
 
+## Support Avalonia
+
+**BTC**: bc1q05wx78qemgy9x6ytl5ljk2xrt00yqargyjm8gx
+
+This will be shared with the community and awarded for significant contributions.
+
 ### Backers
 
 Thank you to all our backers! 🙏 [[Become a backer](https://opencollective.com/Avalonia#backer)]

samples/ControlCatalog.Android/ControlCatalog.Android.csproj

@@ -32,7 +32,7 @@
     <EmbedAssembliesIntoApk>True</EmbedAssembliesIntoApk>
     <BundleAssemblies>False</BundleAssemblies>
     <AndroidCreatePackagePerAbi>False</AndroidCreatePackagePerAbi>
-    <AndroidSupportedAbis>armeabi-v7a;x86</AndroidSupportedAbis>
+    <AndroidSupportedAbis>armeabi-v7a;x86;x86_64</AndroidSupportedAbis>
     <Debugger>Xamarin</Debugger>
     <AndroidEnableMultiDex>False</AndroidEnableMultiDex>
     <AotAssemblies>False</AotAssemblies>
@@ -51,7 +51,7 @@
     <EmbedAssembliesIntoApk>True</EmbedAssembliesIntoApk>
     <BundleAssemblies>False</BundleAssemblies>
     <AndroidCreatePackagePerAbi>False</AndroidCreatePackagePerAbi>
-    <AndroidSupportedAbis>armeabi-v7a,x86</AndroidSupportedAbis>
+    <AndroidSupportedAbis>armeabi-v7a,x86;x86_64</AndroidSupportedAbis>
     <Debugger>Xamarin</Debugger>
     <AotAssemblies>False</AotAssemblies>
     <EnableLLVM>False</EnableLLVM>
@@ -125,6 +125,10 @@
       <Project>{42472427-4774-4c81-8aff-9f27b8e31721}</Project>
       <Name>Avalonia.Layout</Name>
     </ProjectReference>
+    <ProjectReference Include="..\..\src\Avalonia.Themes.Fluent\Avalonia.Themes.Fluent.csproj">
+      <Project>{c42d2fc1-a531-4ed4-84b9-89aec7c962fc}</Project>
+      <Name>Avalonia.Themes.Fluent</Name>
+    </ProjectReference>
     <ProjectReference Include="..\..\src\Avalonia.Visuals\Avalonia.Visuals.csproj">
       <Project>{eb582467-6abb-43a1-b052-e981ba910e3a}</Project>
       <Name>Avalonia.Visuals</Name>

src/Android/Avalonia.Android/AndroidPlatform.cs

@@ -43,11 +43,12 @@ namespace Avalonia.Android
             AvaloniaLocator.CurrentMutable
                 .Bind<IClipboard>().ToTransient<ClipboardImpl>()
                 .Bind<ICursorFactory>().ToTransient<CursorFactory>()
+                .Bind<IWindowingPlatform>().ToConstant(new WindowingPlatformStub())
                 .Bind<IKeyboardDevice>().ToSingleton<AndroidKeyboardDevice>()
                 .Bind<IPlatformSettings>().ToConstant(Instance)
                 .Bind<IPlatformThreadingInterface>().ToConstant(new AndroidThreadingInterface())
                 .Bind<ISystemDialogImpl>().ToTransient<SystemDialogImpl>()
-                .Bind<IPlatformIconLoader>().ToSingleton<PlatformIconLoader>()
+                .Bind<IPlatformIconLoader>().ToSingleton<PlatformIconLoaderStub>()
                 .Bind<IRenderTimer>().ToConstant(new ChoreographerTimer())
                 .Bind<IRenderLoop>().ToConstant(new RenderLoop())
                 .Bind<PlatformHotkeyConfiguration>().ToSingleton<PlatformHotkeyConfiguration>()

src/Android/Avalonia.Android/Stubs.cs

@@ -0,0 +1,56 @@
+using System;
+using System.IO;
+using Avalonia.Platform;
+
+namespace Avalonia.Android
+{
+    class WindowingPlatformStub : IWindowingPlatform
+    {
+        public IWindowImpl CreateWindow() => throw new NotSupportedException();
+
+        public IWindowImpl CreateEmbeddableWindow() => throw new NotSupportedException();
+
+        public ITrayIconImpl CreateTrayIcon() => null;
+    }
+
+    class PlatformIconLoaderStub : IPlatformIconLoader
+    {
+        public IWindowIconImpl LoadIcon(IBitmapImpl bitmap)
+        {
+            using (var stream = new MemoryStream())
+            {
+                bitmap.Save(stream);
+                return LoadIcon(stream);
+            }
+        }
+
+        public IWindowIconImpl LoadIcon(Stream stream)
+        {
+            var ms = new MemoryStream();
+            stream.CopyTo(ms);
+            return new IconStub(ms);
+        }
+
+        public IWindowIconImpl LoadIcon(string fileName)
+        {
+            using (var file = File.Open(fileName, FileMode.Open))
+                return LoadIcon(file);
+        }
+    }
+
+    public class IconStub : IWindowIconImpl
+    {
+        private readonly MemoryStream _ms;
+
+        public IconStub(MemoryStream stream)
+        {
+            _ms = stream;
+        }
+
+        public void Save(Stream outputStream)
+        {
+            _ms.Position = 0;
+            _ms.CopyTo(outputStream);
+        }
+    }
+}

src/Android/Avalonia.AndroidTestApplication/Resources/Resource.Designer.cs

@@ -14,7 +14,7 @@ namespace Avalonia.AndroidTestApplication
 {
 	
 	
-	[global::System.CodeDom.Compiler.GeneratedCodeAttribute("Xamarin.Android.Build.Tasks", "1.0.0.0")]
+	[global::System.CodeDom.Compiler.GeneratedCodeAttribute("Xamarin.Android.Build.Tasks", "12.1.99.62")]
 	public partial class Resource
 	{
 		

src/Avalonia.Animation/Avalonia.Animation.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="..\Avalonia.Base\Avalonia.Base.csproj" />

src/Avalonia.Base/Avalonia.Base.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
     <AssemblyName>Avalonia.Base</AssemblyName>
     <RootNamespace>Avalonia</RootNamespace>
     <AllowUnsafeBlocks>True</AllowUnsafeBlocks>    

src/Avalonia.Base/AvaloniaLocator.cs

@@ -125,6 +125,16 @@ namespace Avalonia
         {
             return (T?) resolver.GetService(typeof (T));
         }
+
+        public static object GetRequiredService(this IAvaloniaDependencyResolver resolver, Type t)
+        {
+            return resolver.GetService(t) ?? throw new InvalidOperationException($"Unable to locate '{t}'.");
+        }
+
+        public static T GetRequiredService<T>(this IAvaloniaDependencyResolver resolver)
+        {
+            return (T?)resolver.GetService(typeof(T)) ?? throw new InvalidOperationException($"Unable to locate '{typeof(T)}'.");
+        }
     }
 }
 

src/Avalonia.Base/Threading/Dispatcher.cs

@@ -56,11 +56,7 @@ namespace Avalonia.Threading
         /// </param>
         public void MainLoop(CancellationToken cancellationToken)
         {
-            var platform = AvaloniaLocator.Current.GetService<IPlatformThreadingInterface>();
+            var platform = AvaloniaLocator.Current.GetRequiredService<IPlatformThreadingInterface>();
-
-            if (platform is null)
-                throw new InvalidOperationException("Unable to locate IPlatformThreadingInterface");
-
             cancellationToken.Register(() => platform.Signal(DispatcherPriority.Send));
             platform.RunLoop(cancellationToken);
         }

src/Avalonia.Base/Utilities/WeakSubscriptionManager.cs

@@ -180,7 +180,7 @@ namespace Avalonia.Utilities
                 {
                     var r = _data[c];
                     if (r?.TryGetTarget(out var sub) == true)
-                        sub.OnEvent(sender, eventArgs);
+                        sub!.OnEvent(sender, eventArgs);
                     else
                         needCompact = true;
                 }

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

@@ -6,7 +6,7 @@
         <BuildOutputTargetFolder>tools</BuildOutputTargetFolder>
         <DefineConstants>$(DefineConstants);BUILDTASK;XAMLX_CECIL_INTERNAL;XAMLX_INTERNAL</DefineConstants>
         <CopyLocalLockFileAssemblies Condition="$(TargetFramework) == 'netstandard2.0'">true</CopyLocalLockFileAssemblies>
-        <NoWarn>NU1605</NoWarn>
+        <NoWarn>NU1605;CS8632</NoWarn>
     </PropertyGroup>
 
     <ItemGroup>

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

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
     <PackageId>Avalonia.Controls.DataGrid</PackageId>
   </PropertyGroup>
   <ItemGroup>

src/Avalonia.Controls/Avalonia.Controls.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="..\Avalonia.Base\Metadata\NullableAttributes.cs" Link="NullableAttributes.cs" />

src/Avalonia.Controls/Button.cs

@@ -304,15 +304,18 @@ namespace Avalonia.Controls
         /// </summary>
         protected virtual void OnClick()
         {
-            OpenFlyout();
+            if (IsEffectivelyEnabled)
+            {
+                OpenFlyout();
 
-            var e = new RoutedEventArgs(ClickEvent);
+                var e = new RoutedEventArgs(ClickEvent);
-            RaiseEvent(e);
+                RaiseEvent(e);
 
-            if (!e.Handled && Command?.CanExecute(CommandParameter) == true)
+                if (!e.Handled && Command?.CanExecute(CommandParameter) == true)
-            {
+                {
-                Command.Execute(CommandParameter);
+                    Command.Execute(CommandParameter);
-                e.Handled = true;
+                    e.Handled = true;
+                }
             }
         }
 

src/Avalonia.Controls/Calendar/CalendarDatePicker.cs

@@ -1,4 +1,4 @@
-// (c) Copyright Microsoft Corporation.
+// (c) Copyright Microsoft Corporation.
 // This source is subject to the Microsoft Public License (Ms-PL).
 // Please see http://go.microsoft.com/fwlink/?LinkID=131993 for details.
 // All other rights reserved.
@@ -425,9 +425,6 @@ namespace Avalonia.Controls
         {
             FocusableProperty.OverrideDefaultValue<CalendarDatePicker>(true);
 
-            DisplayDateProperty.Changed.AddClassHandler<CalendarDatePicker>((x,e) => x.OnDisplayDateChanged(e));
-            DisplayDateStartProperty.Changed.AddClassHandler<CalendarDatePicker>((x,e) => x.OnDisplayDateStartChanged(e));
-            DisplayDateEndProperty.Changed.AddClassHandler<CalendarDatePicker>((x,e) => x.OnDisplayDateEndChanged(e));
             IsDropDownOpenProperty.Changed.AddClassHandler<CalendarDatePicker>((x,e) => x.OnIsDropDownOpenChanged(e));
             SelectedDateProperty.Changed.AddClassHandler<CalendarDatePicker>((x,e) => x.OnSelectedDateChanged(e));
             SelectedDateFormatProperty.Changed.AddClassHandler<CalendarDatePicker>((x,e) => x.OnSelectedDateFormatChanged(e));
@@ -459,18 +456,12 @@ namespace Avalonia.Controls
             if (_calendar != null)
             {
                 _calendar.SelectionMode = CalendarSelectionMode.SingleDate;
-                _calendar.SelectedDate = SelectedDate;
-                SetCalendarDisplayDate(DisplayDate);
-                SetCalendarDisplayDateStart(DisplayDateStart);
-                SetCalendarDisplayDateEnd(DisplayDateEnd);
 
                 _calendar.DayButtonMouseUp += Calendar_DayButtonMouseUp;
                 _calendar.DisplayDateChanged += Calendar_DisplayDateChanged;
                 _calendar.SelectedDatesChanged += Calendar_SelectedDatesChanged;
                 _calendar.PointerReleased += Calendar_PointerReleased;
                 _calendar.KeyDown += Calendar_KeyDown;
-                //_calendar.SizeChanged += new SizeChangedEventHandler(Calendar_SizeChanged);
-                //_calendar.IsTabStop = true;
 
                 var currentBlackoutDays = BlackoutDates;
                 BlackoutDates = _calendar.BlackoutDates;
@@ -587,58 +578,6 @@ namespace Avalonia.Controls
             SetSelectedDate();
         }
         
-        private void SetCalendarDisplayDate(DateTime value)
-        {
-            if (DateTimeHelper.CompareYearMonth(_calendar.DisplayDate, value) != 0)
-            {
-                _calendar.DisplayDate = DisplayDate;
-                if (DateTime.Compare(_calendar.DisplayDate, DisplayDate) != 0)
-                {
-                    DisplayDate = _calendar.DisplayDate;
-                }
-            }
-        }
-        private void OnDisplayDateChanged(AvaloniaPropertyChangedEventArgs e)
-        {
-            if (_calendar != null)
-            {
-                var value = (DateTime)e.NewValue;
-                SetCalendarDisplayDate(value);
-            }
-        }
-        private void SetCalendarDisplayDateStart(DateTime? value)
-        {
-            _calendar.DisplayDateStart = value;
-            if (_calendar.DisplayDateStart.HasValue && DisplayDateStart.HasValue && DateTime.Compare(_calendar.DisplayDateStart.Value, DisplayDateStart.Value) != 0)
-            {
-                DisplayDateStart = _calendar.DisplayDateStart;
-            }
-        }
-        private void OnDisplayDateStartChanged(AvaloniaPropertyChangedEventArgs e)
-        {
-            if (_calendar != null)
-            {
-                var value = (DateTime?)e.NewValue;
-                SetCalendarDisplayDateStart(value);
-            }
-        }
-        private void SetCalendarDisplayDateEnd(DateTime? value)
-        {
-            _calendar.DisplayDateEnd = value;
-            if (_calendar.DisplayDateEnd.HasValue && DisplayDateEnd.HasValue && DateTime.Compare(_calendar.DisplayDateEnd.Value, DisplayDateEnd.Value) != 0)
-            {
-                DisplayDateEnd = _calendar.DisplayDateEnd;
-            }
-
-        }
-        private void OnDisplayDateEndChanged(AvaloniaPropertyChangedEventArgs e)
-        {
-            if (_calendar != null)
-            {
-                var value = (DateTime?)e.NewValue;
-                SetCalendarDisplayDateEnd(value);
-            }
-        }
         private void OnIsDropDownOpenChanged(AvaloniaPropertyChangedEventArgs e)
         {
             var oldValue = (bool)e.OldValue;
@@ -670,11 +609,6 @@ namespace Avalonia.Controls
             var addedDate = (DateTime?)e.NewValue;
             var removedDate = (DateTime?)e.OldValue;
 
-            if (_calendar != null && addedDate != _calendar.SelectedDate)
-            {
-                _calendar.SelectedDate = addedDate;
-            }
-
             if (SelectedDate != null)
             {
                 DateTime day = SelectedDate.Value;

src/Avalonia.Controls/Grid.cs

@@ -978,7 +978,7 @@ namespace Avalonia.Controls
         /// width is not registered in columns.</param>
         /// <param name="forceInfinityV">Passed through to MeasureCell.
         /// When "true" cells' desired height is not registered in rows.</param>
-        /// <param name="hasDesiredSizeUChanged">return true when desired size has changed</param>
+        /// <param name="hasDesiredSizeUChanged">When the method exits, indicates whether the desired size has changed.</param>
         private void MeasureCellsGroup(
             int cellsHead,
             Size referenceSize,

src/Avalonia.Controls/SystemDialog.cs

@@ -66,8 +66,7 @@ namespace Avalonia.Controls
         {
             if(parent == null)
                 throw new ArgumentNullException(nameof(parent));
-            var service = AvaloniaLocator.Current.GetService<ISystemDialogImpl>() ??
+            var service = AvaloniaLocator.Current.GetRequiredService<ISystemDialogImpl>();
-                throw new InvalidOperationException("Unable to locate ISystemDialogImpl.");
             return (await service.ShowFileDialogAsync(this, parent) ??
              Array.Empty<string>()).FirstOrDefault();
         }
@@ -95,8 +94,7 @@ namespace Avalonia.Controls
         {
             if(parent == null)
                 throw new ArgumentNullException(nameof(parent));
-            var service = AvaloniaLocator.Current.GetService<ISystemDialogImpl>() ??
+            var service = AvaloniaLocator.Current.GetRequiredService<ISystemDialogImpl>();
-                throw new InvalidOperationException("Unable to locate ISystemDialogImpl.");
             return service.ShowFileDialogAsync(this, parent);
         }
     }
@@ -125,8 +123,7 @@ namespace Avalonia.Controls
         {
             if(parent == null)
                 throw new ArgumentNullException(nameof(parent));
-            var service = AvaloniaLocator.Current.GetService<ISystemDialogImpl>() ??
+            var service = AvaloniaLocator.Current.GetRequiredService<ISystemDialogImpl>();
-                throw new InvalidOperationException("Unable to locate ISystemDialogImpl.");
             return service.ShowFolderDialogAsync(this, parent);
         }
     }

src/Avalonia.DesignerSupport/Avalonia.DesignerSupport.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
     <!-- WARNING! The designer support version number needs to be frozen 
          To allow projects that implement designer functionality to still
          work with newer versions of Avalonia. This version number only

src/Avalonia.Desktop/Avalonia.Desktop.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-      <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+      <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
       <PackageId>Avalonia.Desktop</PackageId>
   </PropertyGroup>
 

src/Avalonia.DesktopRuntime/Avalonia.DesktopRuntime.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net461;netcoreapp2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net461;netcoreapp2.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>

src/Avalonia.Diagnostics/Avalonia.Diagnostics.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
     <RootNamespace>Avalonia</RootNamespace>
     <PackageId>Avalonia.Diagnostics</PackageId>
   </PropertyGroup>

src/Avalonia.Diagnostics/Diagnostics/ViewModels/TreePageViewModel.cs

@@ -86,14 +86,15 @@ namespace Avalonia.Diagnostics.ViewModels
         public void SelectControl(IControl control)
         {
             var node = default(TreeNode);
+            IControl? c = control;
 
-            while (node == null && control != null)
+            while (node == null && c != null)
             {
-                node = FindNode(control);
+                node = FindNode(c);
 
                 if (node == null)
                 {
-                    control = control.GetVisualParent<IControl>();
+                    c = c.GetVisualParent<IControl>();
                 }
             }
 

src/Avalonia.Dialogs/Avalonia.Dialogs.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>

src/Avalonia.FreeDesktop/Avalonia.FreeDesktop.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>

src/Avalonia.Headless.Vnc/Avalonia.Headless.Vnc.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-      <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+      <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
     </PropertyGroup>
 
     <ItemGroup>

src/Avalonia.Headless/Avalonia.Headless.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
 
   </PropertyGroup>
   <ItemGroup>

src/Avalonia.Input/AccessKeyHandler.cs

@@ -188,7 +188,7 @@ namespace Avalonia.Input
                 // If the menu is open, only match controls in the menu's visual tree.
                 if (menuIsOpen)
                 {
-                    matches = matches.Where(x => MainMenu.IsVisualAncestorOf(x));
+                    matches = matches.Where(x => x is not null && MainMenu!.IsVisualAncestorOf(x));
                 }
 
                 var match = matches.FirstOrDefault();

src/Avalonia.Input/Avalonia.Input.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="..\Avalonia.Base\Metadata\NullableAttributes.cs" Link="NullableAttributes.cs" />

src/Avalonia.Input/GestureRecognizers/ScrollGestureRecognizer.cs

@@ -71,7 +71,7 @@ namespace Avalonia.Input.GestureRecognizers
                 EndGesture();
                 _tracking = e.Pointer;
                 _gestureId = ScrollGestureEventArgs.GetNextFreeId();;
-                _trackedRootPoint = e.GetPosition(null);
+                _trackedRootPoint = e.GetPosition(_target);
             }
         }
 
@@ -85,7 +85,7 @@ namespace Avalonia.Input.GestureRecognizers
         {
             if (e.Pointer == _tracking)
             {
-                var rootPoint = e.GetPosition(null);
+                var rootPoint = e.GetPosition(_target);
                 if (!_scrolling)
                 {
                     if (CanHorizontallyScroll && Math.Abs(_trackedRootPoint.X - rootPoint.X) > ScrollStartDistance)

src/Avalonia.Input/Gestures.cs

@@ -6,6 +6,7 @@ namespace Avalonia.Input
 {
     public static class Gestures
     {
+        private static bool s_isDoubleTapped = false;
         public static readonly RoutedEvent<TappedEventArgs> TappedEvent = RoutedEvent.Register<TappedEventArgs>(
             "Tapped",
             RoutingStrategies.Bubble,
@@ -81,20 +82,23 @@ namespace Avalonia.Input
                 var e = (PointerPressedEventArgs)ev;
                 var visual = (IVisual)ev.Source;
 
-#pragma warning disable CS0618 // Type or member is obsolete
+                if (e.ClickCount <= 1)
-                var clickCount = e.ClickCount;
-#pragma warning restore CS0618 // Type or member is obsolete
-                if (clickCount <= 1)
                 {
+                    s_isDoubleTapped = false;
                     s_lastPress.SetTarget(ev.Source);
                 }
-                else if (clickCount == 2 && e.GetCurrentPoint(visual).Properties.IsLeftButtonPressed)
+                else if (e.ClickCount % 2 == 0 && e.GetCurrentPoint(visual).Properties.IsLeftButtonPressed)
                 {
                     if (s_lastPress.TryGetTarget(out var target) && target == e.Source)
                     {
+                        s_isDoubleTapped = true;
                         e.Source.RaiseEvent(new TappedEventArgs(DoubleTappedEvent, e));
                     }
                 }
+                else
+                {
+                    s_isDoubleTapped = false;
+                }
             }
         }
 
@@ -112,7 +116,9 @@ namespace Avalonia.Input
                         {
                             e.Source.RaiseEvent(new TappedEventArgs(RightTappedEvent, e));
                         }
-                        else
+                        //s_isDoubleTapped needed here to prevent invoking Tapped event when DoubleTapped is called.
+                        //This behaviour matches UWP behaviour.
+                        else if (s_isDoubleTapped == false)
                         {
                             e.Source.RaiseEvent(new TappedEventArgs(TappedEvent, e));
                         }

src/Avalonia.Input/InputElement.cs

@@ -675,7 +675,7 @@ namespace Avalonia.Input
         /// <see cref="IsEffectivelyEnabled"/>.
         /// </summary>
         /// <param name="parent">The parent control.</param>
-        private void UpdateIsEffectivelyEnabled(InputElement parent)
+        private void UpdateIsEffectivelyEnabled(InputElement? parent)
         {
             IsEffectivelyEnabled = IsEnabledCore && (parent?.IsEffectivelyEnabled ?? true);
 

src/Avalonia.Input/Pointer.cs

@@ -54,7 +54,7 @@ namespace Avalonia.Input
                 Captured.DetachedFromVisualTree += OnCaptureDetached;
         }
 
-        IInputElement GetNextCapture(IVisual parent)
+        IInputElement? GetNextCapture(IVisual parent)
         {
             return parent as IInputElement ?? parent.FindAncestorOfType<IInputElement>();
         }

src/Avalonia.Input/PointerEventArgs.cs

@@ -114,7 +114,7 @@ namespace Avalonia.Input
 
     public class PointerPressedEventArgs : PointerEventArgs
     {
-        private readonly int _obsoleteClickCount;
+        private readonly int _clickCount;
 
         public PointerPressedEventArgs(
             IInteractive source,
@@ -123,15 +123,14 @@ namespace Avalonia.Input
             ulong timestamp,
             PointerPointProperties properties,
             KeyModifiers modifiers,
-            int obsoleteClickCount = 1)
+            int clickCount = 1)
             : base(InputElement.PointerPressedEvent, source, pointer, rootVisual, rootVisualPosition,
                 timestamp, properties, modifiers)
         {
-            _obsoleteClickCount = obsoleteClickCount;
+            _clickCount = clickCount;
         }
 
-        [Obsolete("Use DoubleTapped event or Gestures.DoubleRightTapped attached event")]
+        public int ClickCount => _clickCount;
-        public int ClickCount => _obsoleteClickCount;
 
         [Obsolete("Use PointerPressedEventArgs.GetCurrentPoint(this).Properties")]
         public MouseButton MouseButton => Properties.PointerUpdateKind.GetMouseButton();

src/Avalonia.Input/TouchDevice.cs

@@ -2,7 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using Avalonia.Input.Raw;
-using Avalonia.VisualTree;
+using Avalonia.Platform;
 
 namespace Avalonia.Input
 {
@@ -16,7 +16,9 @@ namespace Avalonia.Input
     {
         private readonly Dictionary<long, Pointer> _pointers = new Dictionary<long, Pointer>();
         private bool _disposed;
-        
+        private int _clickCount;
+        private Rect _lastClickRect;
+        private ulong _lastClickTime;
         KeyModifiers GetKeyModifiers(RawInputModifiers modifiers) =>
             (KeyModifiers)(modifiers & RawInputModifiers.KeyboardMask);
 
@@ -27,10 +29,10 @@ namespace Avalonia.Input
                 rv |= RawInputModifiers.LeftMouseButton;
             return rv;
         }
-        
+
         public void ProcessRawEvent(RawInputEventArgs ev)
         {
-            if(_disposed)
+            if (_disposed)
                 return;
             var args = (RawTouchEventArgs)ev;
             if (!_pointers.TryGetValue(args.TouchPointId, out var pointer))
@@ -43,16 +45,40 @@ namespace Avalonia.Input
                     PointerType.Touch, _pointers.Count == 0);
                 pointer.Capture(hit);
             }
-            
+
 
             var target = pointer.Captured ?? args.Root;
             if (args.Type == RawPointerEventType.TouchBegin)
             {
+                if (_pointers.Count > 1)
+                {
+                    _clickCount = 1;
+                    _lastClickTime = 0;
+                    _lastClickRect = new Rect();
+                }
+                else
+                {
+                    var settings = AvaloniaLocator.Current.GetService<IPlatformSettings>();
+                    if (settings == null)
+                    {
+                        throw new Exception("IPlatformSettings can not be null.");
+                    }
+                    if (!_lastClickRect.Contains(args.Position)
+                        || ev.Timestamp - _lastClickTime > settings.DoubleClickTime.TotalMilliseconds)
+                    {
+                        _clickCount = 0;
+                    }
+                    ++_clickCount;
+                    _lastClickTime = ev.Timestamp;
+                    _lastClickRect = new Rect(args.Position, new Size())
+                        .Inflate(new Thickness(16, 16));
+                }
+
                 target.RaiseEvent(new PointerPressedEventArgs(target, pointer,
                     args.Root, args.Position, ev.Timestamp,
                     new PointerPointProperties(GetModifiers(args.InputModifiers, true),
                         PointerUpdateKind.LeftButtonPressed),
-                    GetKeyModifiers(args.InputModifiers)));
+                    GetKeyModifiers(args.InputModifiers), _clickCount));
             }
 
             if (args.Type == RawPointerEventType.TouchEnd)
@@ -84,12 +110,12 @@ namespace Avalonia.Input
                     GetKeyModifiers(args.InputModifiers)));
             }
 
-            
+
         }
 
         public void Dispose()
         {
-            if(_disposed)
+            if (_disposed)
                 return;
             var values = _pointers.Values.ToList();
             _pointers.Clear();
@@ -97,6 +123,6 @@ namespace Avalonia.Input
             foreach (var p in values)
                 p.Dispose();
         }
-        
+
     }
 }

src/Avalonia.Interactivity/Avalonia.Interactivity.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="..\Avalonia.Animation\Avalonia.Animation.csproj" />

src/Avalonia.Layout/AttachedLayout.cs

@@ -12,17 +12,17 @@ namespace Avalonia.Layout
     /// </summary>
     public abstract class AttachedLayout : AvaloniaObject
     {
-        public string LayoutId { get; set; }
+        public string? LayoutId { get; set; }
 
         /// <summary>
         /// Occurs when the measurement state (layout) has been invalidated.
         /// </summary>
-        public event EventHandler MeasureInvalidated;
+        public event EventHandler? MeasureInvalidated;
 
         /// <summary>
         /// Occurs when the arrange state (layout) has been invalidated.
         /// </summary>
-        public event EventHandler ArrangeInvalidated;
+        public event EventHandler? ArrangeInvalidated;
 
         /// <summary>
         /// Initializes any per-container state the layout requires when it is attached to an

src/Avalonia.Layout/Avalonia.Layout.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="..\Avalonia.Animation\Avalonia.Animation.csproj" />
@@ -9,4 +9,5 @@
   </ItemGroup>  
   <Import Project="..\..\build\Rx.props" />
   <Import Project="..\..\build\ApiDiff.props" />
+  <Import Project="..\..\build\NullableEnable.props" />
 </Project>

src/Avalonia.Layout/ElementManager.cs

@@ -13,10 +13,10 @@ namespace Avalonia.Layout
 {
     internal class ElementManager
     {
-        private readonly List<ILayoutable> _realizedElements = new List<ILayoutable>();
+        private readonly List<ILayoutable?> _realizedElements = new List<ILayoutable?>();
         private readonly List<Rect> _realizedElementLayoutBounds = new List<Rect>();
         private int _firstRealizedDataIndex;
-        private VirtualizingLayoutContext _context;
+        private VirtualizingLayoutContext? _context;
 
         private bool IsVirtualizingContext
         {
@@ -58,7 +58,7 @@ namespace Avalonia.Layout
                         // Make sure there is enough space for the bounds.
                         // Note: We could optimize when the count becomes smaller, but keeping
                         // it always up to date is the simplest option for now.
-                        _realizedElementLayoutBounds.Resize(count);
+                        _realizedElementLayoutBounds.Resize(count, default);
                     }
                 }
             }
@@ -66,34 +66,32 @@ namespace Avalonia.Layout
 
         public int GetRealizedElementCount()
         {
-            return IsVirtualizingContext ? _realizedElements.Count : _context.ItemCount;
+            return IsVirtualizingContext ? _realizedElements.Count : _context!.ItemCount;
         }
 
         public ILayoutable GetAt(int realizedIndex)
         {
-            ILayoutable element;
+            ILayoutable? element;
 
             if (IsVirtualizingContext)
             {
-                if (_realizedElements[realizedIndex] == null)
+                element = _realizedElements[realizedIndex];
+
+                if (element == null)
                 {
                     // Sentinel. Create the element now since we need it.
                     int dataIndex = GetDataIndexFromRealizedRangeIndex(realizedIndex);
                     Logger.TryGet(LogEventLevel.Verbose, "Repeater")?.Log(this, "Creating element for sentinal with data index {Index}", dataIndex);
-                    element = _context.GetOrCreateElementAt(
+                    element = _context!.GetOrCreateElementAt(
                         dataIndex,
                         ElementRealizationOptions.ForceCreate | ElementRealizationOptions.SuppressAutoRecycle);
                     _realizedElements[realizedIndex] = element;
                 }
-                else
-                {
-                    element = _realizedElements[realizedIndex];
-                }
             }
             else
             {
                 // realizedIndex and dataIndex are the same (everything is realized)
-                element = _context.GetOrCreateElementAt(
+                element = _context!.GetOrCreateElementAt(
                     realizedIndex,
                     ElementRealizationOptions.ForceCreate | ElementRealizationOptions.SuppressAutoRecycle);
             }
@@ -112,7 +110,7 @@ namespace Avalonia.Layout
             _realizedElementLayoutBounds.Add(default);
         }
 
-        public void Insert(int realizedIndex, int dataIndex, ILayoutable element)
+        public void Insert(int realizedIndex, int dataIndex, ILayoutable? element)
         {
             if (realizedIndex == 0)
             {
@@ -136,7 +134,7 @@ namespace Avalonia.Layout
 
                 if (elementRef != null)
                 {
-                    _context.RecycleElement(elementRef);
+                    _context!.RecycleElement(elementRef);
                 }
             }
 
@@ -203,26 +201,26 @@ namespace Avalonia.Layout
             else
             {
                 // Non virtualized - everything is realized
-                return index >= 0 && index < _context.ItemCount;
+                return index >= 0 && index < _context!.ItemCount;
             }
         }
 
-        public bool IsIndexValidInData(int currentIndex) => (uint)currentIndex < _context.ItemCount;
+        public bool IsIndexValidInData(int currentIndex) => (uint)currentIndex < _context!.ItemCount;
 
-        public ILayoutable GetRealizedElement(int dataIndex)
+        public ILayoutable? GetRealizedElement(int dataIndex)
         {
             return IsVirtualizingContext ?
                 GetAt(GetRealizedRangeIndexFromDataIndex(dataIndex)) :
-                _context.GetOrCreateElementAt(
+                _context!.GetOrCreateElementAt(
                     dataIndex,
                     ElementRealizationOptions.ForceCreate | ElementRealizationOptions.SuppressAutoRecycle);
         }
 
-        public void EnsureElementRealized(bool forward, int dataIndex, string layoutId)
+        public void EnsureElementRealized(bool forward, int dataIndex, string? layoutId)
         {
             if (IsDataIndexRealized(dataIndex) == false)
             {
-                var element = _context.GetOrCreateElementAt(
+                var element = _context!.GetOrCreateElementAt(
                     dataIndex,
                     ElementRealizationOptions.ForceCreate | ElementRealizationOptions.SuppressAutoRecycle);
 
@@ -273,14 +271,14 @@ namespace Avalonia.Layout
                 {
                     case NotifyCollectionChangedAction.Add:
                         {
-                            OnItemsAdded(args.NewStartingIndex, args.NewItems.Count);
+                            OnItemsAdded(args.NewStartingIndex, args.NewItems!.Count);
                         }
                         break;
 
                     case NotifyCollectionChangedAction.Replace:
                         {
-                            int oldSize = args.OldItems.Count;
+                            int oldSize = args.OldItems!.Count;
-                            int newSize = args.NewItems.Count;
+                            int newSize = args.NewItems!.Count;
                             int oldStartIndex = args.OldStartingIndex;
                             int newStartIndex = args.NewStartingIndex;
 
@@ -301,7 +299,7 @@ namespace Avalonia.Layout
 
                                     if (elementRef != null)
                                     {
-                                        _context.RecycleElement(elementRef);
+                                        _context!.RecycleElement(elementRef);
                                         _realizedElements[realizedIndex] = null;
                                     }
                                 }

src/Avalonia.Layout/FlowLayoutAlgorithm.cs

@@ -16,8 +16,8 @@ namespace Avalonia.Layout
         private Size _lastAvailableSize;
         private double _lastItemSpacing;
         private bool _collectionChangePending;
-        private VirtualizingLayoutContext _context;
+        private VirtualizingLayoutContext? _context;
-        private IFlowLayoutAlgorithmDelegates _algorithmCallbacks;
+        private IFlowLayoutAlgorithmDelegates? _algorithmCallbacks;
         private Rect _lastExtent;
         private int _firstRealizedDataIndexInsideRealizationWindow = -1;
         private int _lastRealizedDataIndexInsideRealizationWindow = -1;
@@ -46,7 +46,7 @@ namespace Avalonia.Layout
             }
         }
 
-        private Rect RealizationRect => IsVirtualizingContext ? _context.RealizationRect : new Rect(Size.Infinity);
+        private Rect RealizationRect => IsVirtualizingContext ? _context!.RealizationRect : new Rect(Size.Infinity);
 
         public void InitializeForContext(VirtualizingLayoutContext context, IFlowLayoutAlgorithmDelegates callbacks)
         {
@@ -76,7 +76,7 @@ namespace Avalonia.Layout
             int maxItemsPerLine,
             ScrollOrientation orientation,
             bool disableVirtualization,
-            string layoutId)
+            string? layoutId)
         {
             _orientation.ScrollOrientation = orientation;
 
@@ -87,7 +87,7 @@ namespace Avalonia.Layout
                 layoutId,
                 realizationRect);
 
-            var suggestedAnchorIndex = _context.RecommendedAnchorIndex;
+            var suggestedAnchorIndex = _context!.RecommendedAnchorIndex;
             if (_elementManager.IsIndexValidInData(suggestedAnchorIndex))
             {
                 var anchorRealized = _elementManager.IsDataIndexRealized(suggestedAnchorIndex);
@@ -124,7 +124,7 @@ namespace Avalonia.Layout
             VirtualizingLayoutContext context,
             bool isWrapping,
             LineAlignment lineAlignment,
-            string layoutId)
+            string? layoutId)
         {
             Logger.TryGet(LogEventLevel.Verbose, "Repeater")?.Log(this, "{LayoutId}: ArrangeLayout", layoutId);
             ArrangeVirtualizingLayout(finalSize, lineAlignment, isWrapping, layoutId);
@@ -149,7 +149,7 @@ namespace Avalonia.Layout
             Size availableSize,
             VirtualizingLayoutContext context)
         {
-            var measureSize = _algorithmCallbacks.Algorithm_GetMeasureSize(index, availableSize, context);
+            var measureSize = _algorithmCallbacks!.Algorithm_GetMeasureSize(index, availableSize, context);
             element.Measure(measureSize);
             var provisionalArrangeSize = _algorithmCallbacks.Algorithm_GetProvisionalArrangeSize(index, measureSize, element.DesiredSize, context);
             _algorithmCallbacks.Algorithm_OnElementMeasured(element, index, availableSize, measureSize, element.DesiredSize, provisionalArrangeSize, context);
@@ -161,7 +161,7 @@ namespace Avalonia.Layout
             Size availableSize,
             bool isWrapping,
             double minItemSpacing,
-            string layoutId)
+            string? layoutId)
         {
             int anchorIndex = -1;
             var anchorPosition= new Point();
@@ -170,7 +170,7 @@ namespace Avalonia.Layout
             if (!IsVirtualizingContext)
             {
                 // Non virtualizing host, start generating from the element 0
-                anchorIndex = context.ItemCount > 0 ? 0 : -1;
+                anchorIndex = context!.ItemCount > 0 ? 0 : -1;
             }
             else
             {       
@@ -183,7 +183,7 @@ namespace Avalonia.Layout
                     _lastItemSpacing != minItemSpacing ||
                     _collectionChangePending);
 
-                var suggestedAnchorIndex = _context.RecommendedAnchorIndex;
+                var suggestedAnchorIndex = _context!.RecommendedAnchorIndex;
 
                 var isAnchorSuggestionValid = suggestedAnchorIndex >= 0 &&
                     _elementManager.IsDataIndexRealized(suggestedAnchorIndex);
@@ -191,10 +191,10 @@ namespace Avalonia.Layout
                 if (isAnchorSuggestionValid)
                 {
                     Logger.TryGet(LogEventLevel.Verbose, "Repeater")?.Log(this, "{LayoutId}: Using suggested anchor {Anchor}", layoutId, suggestedAnchorIndex);
-                    anchorIndex = _algorithmCallbacks.Algorithm_GetAnchorForTargetElement(
+                    anchorIndex = _algorithmCallbacks!.Algorithm_GetAnchorForTargetElement(
                         suggestedAnchorIndex,
                         availableSize,
-                        context).Index;
+                        context!).Index;
 
                     if (_elementManager.IsDataIndexRealized(anchorIndex))
                     {
@@ -235,7 +235,7 @@ namespace Avalonia.Layout
 
                     // The anchor is based on the realization window because a connected ItemsRepeater might intersect the realization window
                     // but not the visible window. In that situation, we still need to produce a valid anchor.
-                    var anchorInfo = _algorithmCallbacks.Algorithm_GetAnchorForRealizationRect(availableSize, context);
+                    var anchorInfo = _algorithmCallbacks!.Algorithm_GetAnchorForRealizationRect(availableSize, context!);
                     anchorIndex = anchorInfo.Index;
                     anchorPosition = _orientation.MinorMajorPoint(0, anchorInfo.Offset);
                 }
@@ -259,12 +259,12 @@ namespace Avalonia.Layout
                     Logger.TryGet(LogEventLevel.Verbose, "Repeater")?.Log(this, "{LayoutId} Disconnected Window - throwing away all realized elements", layoutId);
                     _elementManager.ClearRealizedRange();
 
-                    var anchor = _context.GetOrCreateElementAt(anchorIndex, ElementRealizationOptions.ForceCreate | ElementRealizationOptions.SuppressAutoRecycle);
+                    var anchor = _context!.GetOrCreateElementAt(anchorIndex, ElementRealizationOptions.ForceCreate | ElementRealizationOptions.SuppressAutoRecycle);
                     _elementManager.Add(anchor, anchorIndex);
                 }
 
                 var anchorElement = _elementManager.GetRealizedElement(anchorIndex);
-                var desiredSize = MeasureElement(anchorElement, anchorIndex, availableSize, _context);
+                var desiredSize = MeasureElement(anchorElement!, anchorIndex, availableSize, _context!);
                 var layoutBounds = new Rect(anchorPosition.X, anchorPosition.Y, desiredSize.Width, desiredSize.Height);
                 _elementManager.SetLayoutBoundsForDataIndex(anchorIndex, layoutBounds);
 
@@ -296,7 +296,7 @@ namespace Avalonia.Layout
             double lineSpacing,
             int maxItemsPerLine,
             bool disableVirtualization,
-            string layoutId)
+            string? layoutId)
         {
             if (anchorIndex != -1)
             {
@@ -322,7 +322,7 @@ namespace Avalonia.Layout
                     // Ensure layout element.
                     _elementManager.EnsureElementRealized(direction == GenerateDirection.Forward, currentIndex, layoutId);
                     var currentElement = _elementManager.GetRealizedElement(currentIndex);
-                    var desiredSize = MeasureElement(currentElement, currentIndex, availableSize, _context);
+                    var desiredSize = MeasureElement(currentElement!, currentIndex, availableSize, _context!);
                     ++count;
 
                     // Lay it out.
@@ -333,7 +333,7 @@ namespace Avalonia.Layout
                     if (direction == GenerateDirection.Forward)
                     {
                         double remainingSpace = _orientation.Minor(availableSize) - (_orientation.MinorStart(previousElementBounds) + _orientation.MinorSize(previousElementBounds) + minItemSpacing + _orientation.Minor(desiredSize));
-                        if (countInLine >= maxItemsPerLine || _algorithmCallbacks.Algorithm_ShouldBreakLine(currentIndex, remainingSpace))
+                        if (countInLine >= maxItemsPerLine || _algorithmCallbacks!.Algorithm_ShouldBreakLine(currentIndex, remainingSpace))
                         {
                             // No more space in this row. wrap to next row.
                             _orientation.SetMinorStart(ref currentBounds, 0);
@@ -371,7 +371,7 @@ namespace Avalonia.Layout
                     {
                         // Backward 
                         double remainingSpace = _orientation.MinorStart(previousElementBounds) - (_orientation.Minor(desiredSize) + minItemSpacing);
-                        if (countInLine >= maxItemsPerLine || _algorithmCallbacks.Algorithm_ShouldBreakLine(currentIndex, remainingSpace))
+                        if (countInLine >= maxItemsPerLine || _algorithmCallbacks!.Algorithm_ShouldBreakLine(currentIndex, remainingSpace))
                         {
                             // Does not fit, wrap to the previous row
                             var availableSizeMinor = _orientation.Minor(availableSize);
@@ -432,13 +432,13 @@ namespace Avalonia.Layout
                 // account for that element in the indices inside the realization window.
                 if (direction == GenerateDirection.Forward)
                 {
-                    int dataCount = _context.ItemCount;
+                    int dataCount = _context!.ItemCount;
                     _lastRealizedDataIndexInsideRealizationWindow = previousIndex == dataCount - 1 ? dataCount - 1 : previousIndex - 1;
                     _lastRealizedDataIndexInsideRealizationWindow = Math.Max(0, _lastRealizedDataIndexInsideRealizationWindow);
                 }
                 else
                 {
-                    int dataCount = _context.ItemCount;
+                    int dataCount = _context!.ItemCount;
                     _firstRealizedDataIndexInsideRealizationWindow = previousIndex == 0 ? 0 : previousIndex + 1;
                     _firstRealizedDataIndexInsideRealizationWindow = Math.Min(dataCount - 1, _firstRealizedDataIndexInsideRealizationWindow);
                 }
@@ -454,7 +454,7 @@ namespace Avalonia.Layout
         {
             _elementManager.ClearRealizedRange();
             // FlowLayout requires that the anchor is the first element in the row.
-            var internalAnchor = _algorithmCallbacks.Algorithm_GetAnchorForTargetElement(index, availableSize, context);
+            var internalAnchor = _algorithmCallbacks!.Algorithm_GetAnchorForTargetElement(index, availableSize, context);
 
             // No need to set the position of the anchor.
             // (0,0) is fine for now since the extent can
@@ -487,7 +487,7 @@ namespace Avalonia.Layout
             }
             else
             {
-                var realizationRect = _context.RealizationRect;
+                var realizationRect = _context!.RealizationRect;
                 var elementBounds = _elementManager.GetLayoutBoundsForDataIndex(index);
 
                 var elementMajorStart = _orientation.MajorStart(elementBounds);
@@ -510,11 +510,11 @@ namespace Avalonia.Layout
             return shouldContinue;
         }
 
-        private Rect EstimateExtent(Size availableSize, string layoutId)
+        private Rect EstimateExtent(Size availableSize, string? layoutId)
         {
-            ILayoutable firstRealizedElement = null;
+            ILayoutable? firstRealizedElement = null;
             Rect firstBounds = new Rect();
-            ILayoutable lastRealizedElement = null;
+            ILayoutable? lastRealizedElement = null;
             Rect lastBounds = new Rect();
             int firstDataIndex = -1;
             int lastDataIndex = -1;
@@ -531,9 +531,9 @@ namespace Avalonia.Layout
                 lastBounds = _elementManager.GetLayoutBoundsForRealizedIndex(last);
             }
 
-            Rect extent = _algorithmCallbacks.Algorithm_GetExtent(
+            Rect extent = _algorithmCallbacks!.Algorithm_GetExtent(
                 availableSize,
-                _context,
+                _context!,
                 firstRealizedElement,
                 firstDataIndex,
                 firstBounds,
@@ -563,7 +563,7 @@ namespace Avalonia.Layout
                         if (_orientation.MajorStart(currentBounds) != currentLineOffset)
                         {
                             // Staring a new line
-                            _algorithmCallbacks.Algorithm_OnLineArranged(currentDataIndex - countInLine, countInLine, currentLineSize, _context);
+                            _algorithmCallbacks!.Algorithm_OnLineArranged(currentDataIndex - countInLine, countInLine, currentLineSize, _context!);
                             countInLine = 0;
                             currentLineOffset = _orientation.MajorStart(currentBounds);
                             currentLineSize = 0;
@@ -575,7 +575,7 @@ namespace Avalonia.Layout
                     }
 
                     // Raise for the last line.
-                    _algorithmCallbacks.Algorithm_OnLineArranged(_lastRealizedDataIndexInsideRealizationWindow - countInLine + 1, countInLine, currentLineSize, _context);
+                    _algorithmCallbacks!.Algorithm_OnLineArranged(_lastRealizedDataIndexInsideRealizationWindow - countInLine + 1, countInLine, currentLineSize, _context!);
                 }
             }
         }
@@ -584,7 +584,7 @@ namespace Avalonia.Layout
             Size finalSize,
             LineAlignment lineAlignment,
             bool isWrapping,
-            string layoutId)
+            string? layoutId)
         {
             // Walk through the realized elements one line at a time and 
             // align them, Then call element.Arrange with the arranged bounds.
@@ -636,7 +636,7 @@ namespace Avalonia.Layout
             LineAlignment lineAlignment,
             bool isWrapping,
             Size finalSize,
-            string layoutId)
+            string? layoutId)
         {
             for (int rangeIndex = lineStartIndex; rangeIndex < lineStartIndex + countInLine; ++rangeIndex)
             {
@@ -723,11 +723,11 @@ namespace Avalonia.Layout
         {
             if (IsVirtualizingContext)
             {
-                _context.LayoutOrigin = new Point(_lastExtent.X, _lastExtent.Y);
+                _context!.LayoutOrigin = new Point(_lastExtent.X, _lastExtent.Y);
             }
         }
 
-        public ILayoutable GetElementIfRealized(int dataIndex)
+        public ILayoutable? GetElementIfRealized(int dataIndex)
         {
             if (_elementManager.IsDataIndexRealized(dataIndex))
             {

src/Avalonia.Layout/IFlowLayoutAlgorithmDelegates.cs

@@ -21,10 +21,10 @@ namespace Avalonia.Layout
         Rect Algorithm_GetExtent(
             Size availableSize,
             VirtualizingLayoutContext context,
-            ILayoutable firstRealized,
+            ILayoutable? firstRealized,
             int firstRealizedItemIndex,
             Rect firstRealizedLayoutBounds,
-            ILayoutable lastRealized,
+            ILayoutable? lastRealized,
             int lastRealizedItemIndex,
             Rect lastRealizedLayoutBounds);
         void Algorithm_OnElementMeasured(

src/Avalonia.Layout/LayoutContext.cs

@@ -14,7 +14,7 @@ namespace Avalonia.Layout
         /// <summary>
         /// Gets or sets an object that represents the state of a layout.
         /// </summary>
-        public object LayoutState 
+        public object? LayoutState 
         {
             get => LayoutStateCore;
             set => LayoutStateCore = value;
@@ -23,6 +23,6 @@ namespace Avalonia.Layout
         /// <summary>
         /// Implements the behavior of <see cref="LayoutState"/> in a derived or custom LayoutContext.
         /// </summary>
-        protected virtual object LayoutStateCore { get; set; }
+        protected virtual object? LayoutStateCore { get; set; }
     }
 }

src/Avalonia.Layout/LayoutContextAdapter.cs

@@ -16,7 +16,7 @@ namespace Avalonia.Layout
             _nonVirtualizingContext = nonVirtualizingContext;
         }
 
-        protected override object LayoutStateCore 
+        protected override object? LayoutStateCore 
         { 
             get => _nonVirtualizingContext.LayoutState;
             set => _nonVirtualizingContext.LayoutState = value; 

src/Avalonia.Layout/LayoutHelper.cs

@@ -101,7 +101,7 @@ namespace Avalonia.Layout
 
             if (result == 0 || double.IsNaN(result) || double.IsInfinity(result))
             {
-                throw new Exception($"Invalid LayoutScaling returned from {visualRoot.GetType()}");
+                throw new Exception($"Invalid LayoutScaling returned from {visualRoot!.GetType()}");
             }
 
             return result;

src/Avalonia.Layout/LayoutQueue.cs

@@ -5,6 +5,7 @@ using System.Collections.Generic;
 namespace Avalonia.Layout
 {
     internal class LayoutQueue<T> : IReadOnlyCollection<T>, IDisposable
+        where T : notnull
     {
         private struct Info
         {

src/Avalonia.Layout/Layoutable.cs

@@ -794,7 +794,7 @@ namespace Avalonia.Layout
         /// </summary>
         /// <param name="sender">The sender.</param>
         /// <param name="e">The event args.</param>
-        private void LayoutManagedLayoutUpdated(object sender, EventArgs e) => _layoutUpdated?.Invoke(this, e);
+        private void LayoutManagedLayoutUpdated(object? sender, EventArgs e) => _layoutUpdated?.Invoke(this, e);
 
         /// <summary>
         /// Tests whether any of a <see cref="Rect"/>'s properties include negative values,

src/Avalonia.Layout/NonVirtualizingLayoutContext.cs

@@ -12,7 +12,7 @@ namespace Avalonia.Layout
     /// </summary>
     public abstract class NonVirtualizingLayoutContext : LayoutContext
     {
-        private VirtualizingLayoutContext _contextAdapter;
+        private VirtualizingLayoutContext? _contextAdapter;
 
         /// <summary>
         /// Gets the collection of child controls from the container that provides the context.
@@ -26,6 +26,6 @@ namespace Avalonia.Layout
         protected abstract IReadOnlyList<ILayoutable> ChildrenCore { get; }
 
         internal VirtualizingLayoutContext GetVirtualizingContextAdapter() =>
-            _contextAdapter ?? (_contextAdapter = new LayoutContextAdapter(this));
+            _contextAdapter ??= new LayoutContextAdapter(this);
     }
 }

src/Avalonia.Layout/StackLayout.cs

@@ -78,10 +78,10 @@ namespace Avalonia.Layout
         internal Rect GetExtent(
             Size availableSize,
             VirtualizingLayoutContext context,
-            ILayoutable firstRealized,
+            ILayoutable? firstRealized,
             int firstRealizedItemIndex,
             Rect firstRealizedLayoutBounds,
-            ILayoutable lastRealized,
+            ILayoutable? lastRealized,
             int lastRealizedItemIndex,
             Rect lastRealizedLayoutBounds)
         {
@@ -89,7 +89,7 @@ namespace Avalonia.Layout
 
             // Constants
             int itemsCount = context.ItemCount;
-            var stackState = (StackLayoutState)context.LayoutState;
+            var stackState = (StackLayoutState)context.LayoutState!;
             double averageElementSize = GetAverageElementSize(availableSize, context, stackState) + Spacing;
 
             _orientation.SetMinorSize(ref extent, stackState.MaxArrangeBounds);
@@ -131,7 +131,7 @@ namespace Avalonia.Layout
         {
             if (context is VirtualizingLayoutContext virtualContext)
             {
-                var stackState = (StackLayoutState)virtualContext.LayoutState;
+                var stackState = (StackLayoutState)virtualContext.LayoutState!;
                 var provisionalArrangeSizeWinRt = provisionalArrangeSize;
                 stackState.OnElementMeasured(
                     index,
@@ -177,7 +177,7 @@ namespace Avalonia.Layout
             if (targetIndex >= 0 && targetIndex < itemsCount)
             {
                 index = targetIndex;
-                var state = (StackLayoutState)context.LayoutState;
+                var state = (StackLayoutState)context.LayoutState!;
                 double averageElementSize = GetAverageElementSize(availableSize, context, state) + Spacing;
                 offset = index * averageElementSize + _orientation.MajorStart(state.FlowAlgorithm.LastExtent);
             }
@@ -188,10 +188,10 @@ namespace Avalonia.Layout
         Rect IFlowLayoutAlgorithmDelegates.Algorithm_GetExtent(
             Size availableSize,
             VirtualizingLayoutContext context,
-            ILayoutable firstRealized,
+            ILayoutable? firstRealized,
             int firstRealizedItemIndex,
             Rect firstRealizedLayoutBounds,
-            ILayoutable lastRealized,
+            ILayoutable? lastRealized,
             int lastRealizedItemIndex,
             Rect lastRealizedLayoutBounds)
         {
@@ -234,7 +234,7 @@ namespace Avalonia.Layout
             if (itemsCount > 0)
             {
                 var realizationRect = context.RealizationRect;
-                var state = (StackLayoutState)context.LayoutState;
+                var state = (StackLayoutState)context.LayoutState!;
                 var lastExtent = state.FlowAlgorithm.LastExtent;
 
                 double averageElementSize = GetAverageElementSize(availableSize, context, state) + Spacing;
@@ -279,13 +279,13 @@ namespace Avalonia.Layout
 
         protected internal override void UninitializeForContextCore(VirtualizingLayoutContext context)
         {
-            var stackState = (StackLayoutState)context.LayoutState;
+            var stackState = (StackLayoutState)context.LayoutState!;
             stackState.UninitializeForContext(context);
         }
 
         protected internal override Size MeasureOverride(VirtualizingLayoutContext context, Size availableSize)
         {
-            ((StackLayoutState)context.LayoutState).OnMeasureStart();
+            ((StackLayoutState)context.LayoutState!).OnMeasureStart();
 
             var desiredSize = GetFlowAlgorithm(context).Measure(
                 availableSize,
@@ -358,6 +358,6 @@ namespace Avalonia.Layout
 
         private void InvalidateLayout() => InvalidateMeasure();
 
-        private FlowLayoutAlgorithm GetFlowAlgorithm(VirtualizingLayoutContext context) => ((StackLayoutState)context.LayoutState).FlowAlgorithm;
+        private FlowLayoutAlgorithm GetFlowAlgorithm(VirtualizingLayoutContext context) => ((StackLayoutState)context.LayoutState!).FlowAlgorithm;
     }
 }

src/Avalonia.Layout/UniformGridLayout.cs

@@ -258,7 +258,7 @@ namespace Avalonia.Layout
             Size availableSize,
             VirtualizingLayoutContext context)
         {
-            var gridState = (UniformGridLayoutState)context.LayoutState;
+            var gridState = (UniformGridLayoutState)context.LayoutState!;
             return new Size(gridState.EffectiveItemWidth, gridState.EffectiveItemHeight);
         }
 
@@ -268,7 +268,7 @@ namespace Avalonia.Layout
             Size desiredSize,
             VirtualizingLayoutContext context)
         {
-            var gridState = (UniformGridLayoutState)context.LayoutState;
+            var gridState = (UniformGridLayoutState)context.LayoutState!;
             return new Size(gridState.EffectiveItemWidth, gridState.EffectiveItemHeight);
         }
 
@@ -285,7 +285,7 @@ namespace Avalonia.Layout
             var realizationRect = context.RealizationRect;
             if (itemsCount > 0 && _orientation.MajorSize(realizationRect) > 0)
             {
-                var gridState = (UniformGridLayoutState)context.LayoutState;
+                var gridState = (UniformGridLayoutState)context.LayoutState!;
                 var lastExtent = gridState.FlowAlgorithm.LastExtent;
                 var itemsPerLine = Math.Min( // note use of unsigned ints
                     Math.Max(1u, (uint)(_orientation.Minor(availableSize) / GetMinorSizeWithSpacing(context))),
@@ -324,7 +324,7 @@ namespace Avalonia.Layout
                     Math.Max(1u, _maximumRowsOrColumns));
                 int indexOfFirstInLine = (targetIndex / itemsPerLine) * itemsPerLine;
                 index = indexOfFirstInLine;
-                var state = context.LayoutState as UniformGridLayoutState;
+                var state = (UniformGridLayoutState)context.LayoutState!;
                 offset = _orientation.MajorStart(GetLayoutRectForDataIndex(availableSize, indexOfFirstInLine, state.FlowAlgorithm.LastExtent, context));
             }
 
@@ -338,10 +338,10 @@ namespace Avalonia.Layout
         Rect IFlowLayoutAlgorithmDelegates.Algorithm_GetExtent(
             Size availableSize,
             VirtualizingLayoutContext context,
-            ILayoutable firstRealized,
+            ILayoutable? firstRealized,
             int firstRealizedItemIndex,
             Rect firstRealizedLayoutBounds,
-            ILayoutable lastRealized,
+            ILayoutable? lastRealized,
             int lastRealizedItemIndex,
             Rect lastRealizedLayoutBounds)
         {
@@ -421,7 +421,7 @@ namespace Avalonia.Layout
 
         protected internal override void UninitializeForContextCore(VirtualizingLayoutContext context)
         {
-            var gridState = (UniformGridLayoutState)context.LayoutState;
+            var gridState = (UniformGridLayoutState)context.LayoutState!;
             gridState.UninitializeForContext(context);
         }
 
@@ -429,7 +429,7 @@ namespace Avalonia.Layout
         {
             // Set the width and height on the grid state. If the user already set them then use the preset. 
             // If not, we have to measure the first element and get back a size which we're going to be using for the rest of the items.
-            var gridState = (UniformGridLayoutState)context.LayoutState;
+            var gridState = (UniformGridLayoutState)context.LayoutState!;
             gridState.EnsureElementSize(availableSize, context, _minItemWidth, _minItemHeight, _itemsStretch, Orientation, MinRowSpacing, MinColumnSpacing, _maximumRowsOrColumns);
 
             var desiredSize = GetFlowAlgorithm(context).Measure(
@@ -467,7 +467,7 @@ namespace Avalonia.Layout
             // Always invalidate layout to keep the view accurate.
             InvalidateLayout();
 
-            var gridState = (UniformGridLayoutState)context.LayoutState;
+            var gridState = (UniformGridLayoutState)context.LayoutState!;
             gridState.ClearElementOnDataSourceChange(context, args);
         }
 
@@ -517,7 +517,7 @@ namespace Avalonia.Layout
         private double GetMinorSizeWithSpacing(VirtualizingLayoutContext context)
         {
             var minItemSpacing = MinItemSpacing;
-            var gridState = (UniformGridLayoutState)context.LayoutState;
+            var gridState = (UniformGridLayoutState)context.LayoutState!;
             return _orientation.ScrollOrientation == ScrollOrientation.Vertical?
                 gridState.EffectiveItemWidth + minItemSpacing :
                 gridState.EffectiveItemHeight + minItemSpacing;
@@ -526,7 +526,7 @@ namespace Avalonia.Layout
         private double GetMajorSizeWithSpacing(VirtualizingLayoutContext context)
         {
             var lineSpacing = LineSpacing;
-            var gridState = (UniformGridLayoutState)context.LayoutState;
+            var gridState = (UniformGridLayoutState)context.LayoutState!;
             return _orientation.ScrollOrientation == ScrollOrientation.Vertical ?
                 gridState.EffectiveItemHeight + lineSpacing :
                 gridState.EffectiveItemWidth + lineSpacing;
@@ -544,7 +544,7 @@ namespace Avalonia.Layout
             int rowIndex = (int)(index / itemsPerLine);
             int indexInRow = index - (rowIndex * itemsPerLine);
 
-            var gridState = (UniformGridLayoutState)context.LayoutState;
+            var gridState = (UniformGridLayoutState)context.LayoutState!;
             Rect bounds = _orientation.MinorMajorRect(
                 indexInRow * GetMinorSizeWithSpacing(context) + _orientation.MinorStart(lastExtent),
                 rowIndex * GetMajorSizeWithSpacing(context) + _orientation.MajorStart(lastExtent),
@@ -556,6 +556,6 @@ namespace Avalonia.Layout
 
         private void InvalidateLayout() => InvalidateMeasure();
 
-        private FlowLayoutAlgorithm GetFlowAlgorithm(VirtualizingLayoutContext context) => ((UniformGridLayoutState)context.LayoutState).FlowAlgorithm;
+        private FlowLayoutAlgorithm GetFlowAlgorithm(VirtualizingLayoutContext context) => ((UniformGridLayoutState)context.LayoutState!).FlowAlgorithm;
     }
 }

src/Avalonia.Layout/UniformGridLayoutState.cs

@@ -18,7 +18,7 @@ namespace Avalonia.Layout
         // If it does not, then we need to do context.GetElement(0) at which point we have requested an element and are on point to clear it.
         // If we are responsible for clearing element 0 we keep m_cachedFirstElement valid. 
         // If we are not (because FlowLayoutAlgorithm is holding it for us) then we just null out this field and use the one from FlowLayoutAlgorithm.
-        private ILayoutable _cachedFirstElement;
+        private ILayoutable? _cachedFirstElement;
 
         internal FlowLayoutAlgorithm FlowAlgorithm { get; } = new FlowLayoutAlgorithm();
         internal double EffectiveItemWidth { get; private set; }

src/Avalonia.Layout/Utils/ListUtils.cs

@@ -23,10 +23,5 @@ namespace Avalonia.Layout.Utils
                 list.AddRange(Enumerable.Repeat(value, size - cur));
             }
         }
-
-        public static void Resize<T>(this List<T> list, int count)
-        {
-            Resize(list, count, default);
-        }
     }
 }

src/Avalonia.Layout/VirtualLayoutContextAdapter.cs

@@ -6,14 +6,14 @@ namespace Avalonia.Layout
     public class VirtualLayoutContextAdapter : NonVirtualizingLayoutContext
     {
         private readonly VirtualizingLayoutContext _virtualizingContext;
-        private ChildrenCollection _children;
+        private ChildrenCollection? _children;
 
         public VirtualLayoutContextAdapter(VirtualizingLayoutContext virtualizingContext)
         {
             _virtualizingContext = virtualizingContext;
         }
 
-        protected override object LayoutStateCore
+        protected override object? LayoutStateCore
         {
             get => _virtualizingContext.LayoutState;
             set => _virtualizingContext.LayoutState = value;

src/Avalonia.Layout/VirtualizingLayoutContext.cs

@@ -43,7 +43,7 @@ namespace Avalonia.Layout
     /// </summary>
     public abstract class VirtualizingLayoutContext : LayoutContext
     {
-        private NonVirtualizingLayoutContext _contextAdapter;
+        private NonVirtualizingLayoutContext? _contextAdapter;
 
         /// <summary>
         /// Gets the number of items in the data.

src/Avalonia.Layout/WrapLayout/UvMeasure.cs

@@ -27,7 +27,7 @@ namespace Avalonia.Layout
             }
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             if (obj is UvMeasure measure)
             {

src/Avalonia.Layout/WrapLayout/WrapItem.cs

@@ -20,6 +20,6 @@ namespace Avalonia.Layout
 
         public UvMeasure? Position { get; internal set; }
 
-        public ILayoutable Element { get; internal set; }
+        public ILayoutable? Element { get; internal set; }
     }
 }

src/Avalonia.Layout/WrapLayout/WrapLayout.cs

@@ -88,7 +88,7 @@ namespace Avalonia.Layout
         /// <inheritdoc />
         protected internal override void OnItemsChangedCore(VirtualizingLayoutContext context, object source, NotifyCollectionChangedEventArgs args)
         {
-            var state = (WrapLayoutState)context.LayoutState;
+            var state = (WrapLayoutState)context.LayoutState!;
 
             switch (args.Action)
             {
@@ -126,7 +126,7 @@ namespace Avalonia.Layout
             var realizationBounds = new UvBounds(Orientation, context.RealizationRect);
             var position = UvMeasure.Zero;
 
-            var state = (WrapLayoutState)context.LayoutState;
+            var state = (WrapLayoutState)context.LayoutState!;
             if (state.Orientation != Orientation)
             {
                 state.SetOrientation(Orientation);
@@ -261,7 +261,7 @@ namespace Avalonia.Layout
                 var spacingMeasure = new UvMeasure(Orientation, HorizontalSpacing, VerticalSpacing);
                 var realizationBounds = new UvBounds(Orientation, context.RealizationRect);
 
-                var state = (WrapLayoutState)context.LayoutState;
+                var state = (WrapLayoutState)context.LayoutState!;
                 bool Arrange(WrapItem item, bool isLast = false)
                 {
                     if (item.Measure.HasValue == false)

src/Avalonia.Layout/WrapLayout/WrapLayoutState.cs

@@ -62,8 +62,11 @@ namespace Avalonia.Layout
 
         internal void SetOrientation(Orientation orientation)
         {
-            foreach (var item in _items.Where(i => i.Measure.HasValue))
+            foreach (var item in _items)
             {
+                if (!item.Measure.HasValue)
+                    continue;
+
                 UvMeasure measure = item.Measure.Value;
                 double v = measure.V;
                 measure.V = measure.U;
@@ -120,10 +123,10 @@ namespace Avalonia.Layout
                 }
 
                 lastPosition = item.Position;
-                maxV = Math.Max(maxV, item.Measure.Value.V);
+                maxV = Math.Max(maxV, item.Measure!.Value.V);
             }
 
-            double totalHeight = lastPosition.Value.V + maxV;
+            double totalHeight = lastPosition!.Value.V + maxV;
             if (calculateAverage)
             {
                 return (totalHeight / itemCount) * _context.ItemCount;

src/Avalonia.Native/Avalonia.Native.csproj

@@ -4,7 +4,7 @@
     <PackAvaloniaNative Condition="'$(PackAvaloniaNative)' == ''">$([MSBuild]::IsOSPlatform(OSX))</PackAvaloniaNative>
     <IsPackable>$(PackAvaloniaNative)</IsPackable>
     <IsPackable Condition="'$([MSBuild]::IsOSPlatform(OSX))' == 'True'">true</IsPackable>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 

src/Avalonia.Native/AvaloniaNativeMenuExporter.cs

@@ -142,6 +142,13 @@ namespace Avalonia.Native
 
         private void DoLayoutReset(bool forceUpdate = false)
         {
+            var macOpts = AvaloniaLocator.Current.GetService<MacOSPlatformOptions>();
+
+            if (macOpts != null && macOpts.DisableNativeMenus)
+            {
+                return;
+            }
+
             if (_resetQueued || forceUpdate)
             {
                 _resetQueued = false;

src/Avalonia.Native/AvaloniaNativePlatformExtensions.cs

@@ -73,5 +73,10 @@ namespace Avalonia
         /// You can prevent Avalonia from adding those items to the OSX Application Menu with this property. The default value is false.
         /// </summary>
         public bool DisableDefaultApplicationMenuItems { get; set; }
+        
+        /// <summary>
+        /// Gets or sets a value indicating whether the native macOS menu bar will be enabled for the application.
+        /// </summary>
+        public bool DisableNativeMenus { get; set; }
     }
 }

src/Avalonia.OpenGL/Avalonia.OpenGL.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+        <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
         <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     </PropertyGroup>
 

src/Avalonia.ReactiveUI/Avalonia.ReactiveUI.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
     <PackageId>Avalonia.ReactiveUI</PackageId>
     <SignAssembly>false</SignAssembly>
   </PropertyGroup>

src/Avalonia.Remote.Protocol/Avalonia.Remote.Protocol.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
     <DefineConstants>AVALONIA_REMOTE_PROTOCOL;$(DefineConstants)</DefineConstants>
     <SignAssembly>true</SignAssembly>
     <AssemblyOriginatorKeyFile>Key.snk</AssemblyOriginatorKeyFile>

src/Avalonia.Styling/Avalonia.Styling.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
     <AssemblyName>Avalonia.Styling</AssemblyName>
     <RootNamespace>Avalonia</RootNamespace>
   </PropertyGroup>
@@ -9,4 +9,5 @@
     <ProjectReference Include="..\Avalonia.Base\Avalonia.Base.csproj" />
   </ItemGroup>
   <Import Project="..\..\build\ApiDiff.props" />
+  <Import Project="..\..\build\NullableEnable.props" />
 </Project>

src/Avalonia.Styling/Controls/ChildNameScope.cs

@@ -15,20 +15,20 @@ namespace Avalonia.Controls
         
         public void Register(string name, object element) => _inner.Register(name, element);
 
-        public SynchronousCompletionAsyncResult<object> FindAsync(string name)
+        public SynchronousCompletionAsyncResult<object?> FindAsync(string name)
         {
             var found = Find(name);
             if (found != null)
-                return new SynchronousCompletionAsyncResult<object>(found);
+                return new SynchronousCompletionAsyncResult<object?>(found);
             // Not found and both current and parent scope are in completed state
             if(IsCompleted)
-                return new SynchronousCompletionAsyncResult<object>(null);
+                return new SynchronousCompletionAsyncResult<object?>(null);
             return DoFindAsync(name);
         }
 
-        public SynchronousCompletionAsyncResult<object> DoFindAsync(string name)
+        public SynchronousCompletionAsyncResult<object?> DoFindAsync(string name)
         {
-            var src = new SynchronousCompletionAsyncResultSource<object>();
+            var src = new SynchronousCompletionAsyncResultSource<object?>();
 
             void ParentSearch()
             {
@@ -56,7 +56,7 @@ namespace Avalonia.Controls
             return src.AsyncResult;
         }
 
-        public object Find(string name)
+        public object? Find(string name)
         {
             var found = _inner.Find(name);
             if (found != null)

src/Avalonia.Styling/Controls/INameScope.cs

@@ -22,14 +22,14 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="name">The name.</param>
         /// <returns>The element, or null if the name was not found.</returns>
-        SynchronousCompletionAsyncResult<object> FindAsync(string name);
+        SynchronousCompletionAsyncResult<object?> FindAsync(string name);
         
         /// <summary>
         /// Finds a named element in the name scope, returns immediately, doesn't traverse the name scope stack
         /// </summary>
         /// <param name="name">The name.</param>
         /// <returns>The element, or null if the name was not found.</returns>
-        object Find(string name);
+        object? Find(string name);
 
         /// <summary>
         /// Marks the name scope as completed, no further registrations will be allowed

src/Avalonia.Styling/Controls/NameScope.cs

@@ -22,8 +22,8 @@ namespace Avalonia.Controls
         
         private readonly Dictionary<string, object> _inner = new Dictionary<string, object>();
 
-        private readonly Dictionary<string, SynchronousCompletionAsyncResultSource<object>> _pendingSearches =
+        private readonly Dictionary<string, SynchronousCompletionAsyncResultSource<object?>> _pendingSearches =
-            new Dictionary<string, SynchronousCompletionAsyncResultSource<object>>();
+            new Dictionary<string, SynchronousCompletionAsyncResultSource<object?>>();
         
         /// <summary>
         /// Gets the value of the attached <see cref="NameScopeProperty"/> on a styled element.
@@ -32,7 +32,7 @@ namespace Avalonia.Controls
         /// <returns>The value of the NameScope attached property.</returns>
         public static INameScope GetNameScope(StyledElement styled)
         {
-            Contract.Requires<ArgumentNullException>(styled != null);
+            _ = styled ?? throw new ArgumentNullException(nameof(styled));
 
             return styled.GetValue(NameScopeProperty);
         }
@@ -44,7 +44,7 @@ namespace Avalonia.Controls
         /// <param name="value">The value to set.</param>
         public static void SetNameScope(StyledElement styled, INameScope value)
         {
-            Contract.Requires<ArgumentNullException>(styled != null);
+            _ = styled ?? throw new ArgumentNullException(nameof(styled));
 
             styled.SetValue(NameScopeProperty, value);
         }
@@ -54,12 +54,11 @@ namespace Avalonia.Controls
         {
             if (IsCompleted)
                 throw new InvalidOperationException("NameScope is completed, no further registrations are allowed");
-            Contract.Requires<ArgumentNullException>(name != null);
-            Contract.Requires<ArgumentNullException>(element != null);
 
-            object existing;
+            _ = name ?? throw new ArgumentNullException(nameof(name));
+            _ = element ?? throw new ArgumentNullException(nameof(element));
 
-            if (_inner.TryGetValue(name, out existing))
+            if (_inner.TryGetValue(name, out var existing))
             {
                 if (existing != element)
                 {
@@ -77,27 +76,26 @@ namespace Avalonia.Controls
             }
         }
 
-        public SynchronousCompletionAsyncResult<object> FindAsync(string name)
+        public SynchronousCompletionAsyncResult<object?> FindAsync(string name)
         {
             var found = Find(name);
             if (found != null)
-                return new SynchronousCompletionAsyncResult<object>(found);
+                return new SynchronousCompletionAsyncResult<object?>(found);
             if (IsCompleted)
-                return new SynchronousCompletionAsyncResult<object>((object)null);
+                return new SynchronousCompletionAsyncResult<object?>(null);
             if (!_pendingSearches.TryGetValue(name, out var tcs))
                 // We are intentionally running continuations synchronously here
-                _pendingSearches[name] = tcs = new SynchronousCompletionAsyncResultSource<object>();
+                _pendingSearches[name] = tcs = new SynchronousCompletionAsyncResultSource<object?>();
 
             return tcs.AsyncResult;
         }
 
         /// <inheritdoc />
-        public object Find(string name)
+        public object? Find(string name)
         {
-            Contract.Requires<ArgumentNullException>(name != null);
+            _ = name ?? throw new ArgumentNullException(nameof(name));
 
-            object result;
+            _inner.TryGetValue(name, out var result);
-            _inner.TryGetValue(name, out result);
             return result;
         }
 

src/Avalonia.Styling/Controls/NameScopeExtensions.cs

@@ -17,11 +17,11 @@ namespace Avalonia.Controls
         /// <param name="nameScope">The name scope.</param>
         /// <param name="name">The name.</param>
         /// <returns>The named element or null if not found.</returns>
-        public static T Find<T>(this INameScope nameScope, string name)
+        public static T? Find<T>(this INameScope nameScope, string name)
             where T : class
         {
-            Contract.Requires<ArgumentNullException>(nameScope != null);
+            _ = nameScope ?? throw new ArgumentNullException(nameof(nameScope));
-            Contract.Requires<ArgumentNullException>(name != null);
+            _ = name ?? throw new ArgumentNullException(nameof(name));
 
             var result = nameScope.Find(name);
 
@@ -31,7 +31,7 @@ namespace Avalonia.Controls
                     $"Expected control '{name}' to be '{typeof(T)} but it was '{result.GetType()}'.");
             }
 
-            return (T)result;
+            return (T?)result;
         }
 
         /// <summary>
@@ -41,11 +41,11 @@ namespace Avalonia.Controls
         /// <param name="anchor">The control to take the name scope from.</param>
         /// <param name="name">The name.</param>
         /// <returns>The named element or null if not found.</returns>
-        public static T Find<T>(this ILogical anchor, string name)
+        public static T? Find<T>(this ILogical anchor, string name)
             where T : class
         {
-            Contract.Requires<ArgumentNullException>(anchor != null);
+            _ = anchor ?? throw new ArgumentNullException(nameof(anchor));
-            Contract.Requires<ArgumentNullException>(name != null);
+            _ = name ?? throw new ArgumentNullException(nameof(name));
             var styledAnchor = anchor as StyledElement;
             if (styledAnchor == null)
                 return null;
@@ -64,8 +64,8 @@ namespace Avalonia.Controls
         public static T Get<T>(this INameScope nameScope, string name)
             where T : class
         {
-            Contract.Requires<ArgumentNullException>(nameScope != null);
+            _ = nameScope ?? throw new ArgumentNullException(nameof(nameScope));
-            Contract.Requires<ArgumentNullException>(name != null);
+            _ = name ?? throw new ArgumentNullException(nameof(name));
 
             var result = nameScope.Find(name);
 
@@ -94,9 +94,9 @@ namespace Avalonia.Controls
         public static T Get<T>(this ILogical anchor, string name)
             where T : class
         {
-            Contract.Requires<ArgumentNullException>(anchor != null);
+            _ = anchor ?? throw new ArgumentNullException(nameof(anchor));
-            Contract.Requires<ArgumentNullException>(name != null);
+            _ = name ?? throw new ArgumentNullException(nameof(name));
-               
+
             var nameScope = (anchor as INameScope) ?? NameScope.GetNameScope((StyledElement)anchor);
             if (nameScope == null)
                 throw new InvalidOperationException(
@@ -105,9 +105,9 @@ namespace Avalonia.Controls
             return nameScope.Get<T>(name);
         }
         
-        public static INameScope FindNameScope(this ILogical control)
+        public static INameScope? FindNameScope(this ILogical control)
         {
-            Contract.Requires<ArgumentNullException>(control != null);
+            _ = control ?? throw new ArgumentNullException(nameof(control));
 
             var scope = control.GetSelfAndLogicalAncestors()
                 .OfType<StyledElement>()

src/Avalonia.Styling/Controls/NameScopeLocator.cs

@@ -11,9 +11,9 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="scope">The scope relative from which the object should be resolved.</param>
         /// <param name="name">The name of the object to find.</param>
-        public static IObservable<object> Track(INameScope scope, string name)
+        public static IObservable<object?> Track(INameScope scope, string name)
         {
-            return new NeverEndingSynchronousCompletionAsyncResultObservable<object>(scope.FindAsync(name));
+            return new NeverEndingSynchronousCompletionAsyncResultObservable<object?>(scope.FindAsync(name));
         }
         
         // This class is implemented in such weird way because for some reason
@@ -22,7 +22,7 @@ namespace Avalonia.Controls
 
         private class NeverEndingSynchronousCompletionAsyncResultObservable<T> : IObservable<T>
         {
-            private T _value;
+            private T? _value;
             private SynchronousCompletionAsyncResult<T>? _asyncResult;
 
             public NeverEndingSynchronousCompletionAsyncResultObservable(SynchronousCompletionAsyncResult<T> task)
@@ -47,7 +47,7 @@ namespace Avalonia.Controls
                         observer.OnNext(_asyncResult.Value.GetResult());
                     });
                 else
-                    observer.OnNext(_value);
+                    observer.OnNext(_value!);
                 
                 return Disposable.Empty;
             }

src/Avalonia.Styling/Controls/PseudoClassesExtensions.cs

@@ -12,7 +12,7 @@ namespace Avalonia.Controls
         /// <param name="value">True to add the pseudoclass or false to remove.</param>
         public static void Set(this IPseudoClasses classes, string name, bool value)
         {
-            Contract.Requires<ArgumentNullException>(classes != null);
+            _ = classes ?? throw new ArgumentNullException(nameof(classes));
 
             if (value)
             {

src/Avalonia.Styling/Controls/ResourceDictionary.cs

@@ -177,7 +177,7 @@ namespace Avalonia.Controls
             }
         }
 
-        private void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
+        private void OnCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
         {
             Owner?.NotifyHostedResourcesChanged(ResourcesChangedEventArgs.Empty);
         }

src/Avalonia.Styling/Controls/ResourceNodeExtensions.cs

@@ -109,7 +109,7 @@ namespace Avalonia.Controls
                 observer.OnNext(Convert(_target.FindResource(_key)));
             }
 
-            private void ResourcesChanged(object sender, ResourcesChangedEventArgs e)
+            private void ResourcesChanged(object? sender, ResourcesChangedEventArgs e)
             {
                 PublishNext(Convert(_target.FindResource(_key)));
             }
@@ -159,7 +159,7 @@ namespace Avalonia.Controls
                 }
             }
 
-            private void OwnerChanged(object sender, EventArgs e)
+            private void OwnerChanged(object? sender, EventArgs e)
             {
                 if (_owner is object)
                 {
@@ -176,7 +176,7 @@ namespace Avalonia.Controls
                 PublishNext();
             }
 
-            private void ResourcesChanged(object sender, ResourcesChangedEventArgs e)
+            private void ResourcesChanged(object? sender, ResourcesChangedEventArgs e)
             {
                 PublishNext();
             }

src/Avalonia.Styling/INamed.cs

@@ -8,6 +8,6 @@ namespace Avalonia
         /// <summary>
         /// Gets the element name.
         /// </summary>
-        string Name { get; }
+        string? Name { get; }
     }
 }

src/Avalonia.Styling/LogicalTree/ControlLocator.cs

@@ -9,19 +9,19 @@ namespace Avalonia.LogicalTree
     /// </summary>
     public static class ControlLocator
     {
-        public static IObservable<ILogical> Track(ILogical relativeTo, int ancestorLevel, Type ancestorType = null)
+        public static IObservable<ILogical?> Track(ILogical relativeTo, int ancestorLevel, Type? ancestorType = null)
         {
             return new ControlTracker(relativeTo, ancestorLevel, ancestorType);
         }
 
-        private class ControlTracker : LightweightObservableBase<ILogical>
+        private class ControlTracker : LightweightObservableBase<ILogical?>
         {
             private readonly ILogical _relativeTo;
             private readonly int _ancestorLevel;
-            private readonly Type _ancestorType;
+            private readonly Type? _ancestorType;
-            private ILogical _value;
+            private ILogical? _value;
 
-            public ControlTracker(ILogical relativeTo, int ancestorLevel, Type ancestorType)
+            public ControlTracker(ILogical relativeTo, int ancestorLevel, Type? ancestorType)
             {
                 _relativeTo = relativeTo;
                 _ancestorLevel = ancestorLevel;
@@ -43,18 +43,18 @@ namespace Avalonia.LogicalTree
                 _value = null;
             }
 
-            protected override void Subscribed(IObserver<ILogical> observer, bool first)
+            protected override void Subscribed(IObserver<ILogical?> observer, bool first)
             {
                 observer.OnNext(_value);
             }
 
-            private void Attached(object sender, LogicalTreeAttachmentEventArgs e)
+            private void Attached(object? sender, LogicalTreeAttachmentEventArgs e)
             {
                 Update();
                 PublishNext(_value);
             }
 
-            private void Detached(object sender, LogicalTreeAttachmentEventArgs e)
+            private void Detached(object? sender, LogicalTreeAttachmentEventArgs e)
             {
                 _value = null;
                 PublishNext(null);

src/Avalonia.Styling/LogicalTree/ILogical.cs

@@ -12,12 +12,12 @@ namespace Avalonia.LogicalTree
         /// <summary>
         /// Raised when the control is attached to a rooted logical tree.
         /// </summary>
-        event EventHandler<LogicalTreeAttachmentEventArgs> AttachedToLogicalTree;
+        event EventHandler<LogicalTreeAttachmentEventArgs>? AttachedToLogicalTree;
 
         /// <summary>
         /// Raised when the control is detached from a rooted logical tree.
         /// </summary>
-        event EventHandler<LogicalTreeAttachmentEventArgs> DetachedFromLogicalTree;
+        event EventHandler<LogicalTreeAttachmentEventArgs>? DetachedFromLogicalTree;
 
         /// <summary>
         /// Gets a value indicating whether the element is attached to a rooted logical tree.
@@ -27,7 +27,7 @@ namespace Avalonia.LogicalTree
         /// <summary>
         /// Gets the logical parent.
         /// </summary>
-        ILogical LogicalParent { get; }
+        ILogical? LogicalParent { get; }
 
         /// <summary>
         /// Gets the logical children.

src/Avalonia.Styling/LogicalTree/LogicalExtensions.cs

@@ -15,14 +15,14 @@ namespace Avalonia.LogicalTree
         /// <returns>The logical's ancestors.</returns>
         public static IEnumerable<ILogical> GetLogicalAncestors(this ILogical logical)
         {
-            Contract.Requires<ArgumentNullException>(logical != null);
+            _ = logical ?? throw new ArgumentNullException(nameof(logical));
 
-            logical = logical.LogicalParent;
+            ILogical? l = logical.LogicalParent;
 
-            while (logical != null)
+            while (l != null)
             {
-                yield return logical;
+                yield return l;
-                logical = logical.LogicalParent;
+                l = l.LogicalParent;
             }
         }
 
@@ -48,14 +48,14 @@ namespace Avalonia.LogicalTree
         /// <param name="logical">The logical.</param>
         /// <param name="includeSelf">If given logical should be included in search.</param>
         /// <returns>First ancestor of given type.</returns>
-        public static T FindLogicalAncestorOfType<T>(this ILogical logical, bool includeSelf = false) where T : class
+        public static T? FindLogicalAncestorOfType<T>(this ILogical logical, bool includeSelf = false) where T : class
         {
             if (logical is null)
             {
                 return null;
             }
 
-            ILogical parent = includeSelf ? logical : logical.LogicalParent;
+            var parent = includeSelf ? logical : logical.LogicalParent;
 
             while (parent != null)
             {
@@ -120,7 +120,7 @@ namespace Avalonia.LogicalTree
         /// <param name="logical">The logical.</param>
         /// <param name="includeSelf">If given logical should be included in search.</param>
         /// <returns>First descendant of given type.</returns>
-        public static T FindLogicalDescendantOfType<T>(this ILogical logical, bool includeSelf = false) where T : class
+        public static T? FindLogicalDescendantOfType<T>(this ILogical logical, bool includeSelf = false) where T : class
         {
             if (logical is null)
             {
@@ -140,7 +140,7 @@ namespace Avalonia.LogicalTree
         /// </summary>
         /// <param name="logical">The logical.</param>
         /// <returns>The parent, or null if the logical is unparented.</returns>
-        public static ILogical GetLogicalParent(this ILogical logical)
+        public static ILogical? GetLogicalParent(this ILogical logical)
         {
             return logical.LogicalParent;
         }
@@ -153,7 +153,7 @@ namespace Avalonia.LogicalTree
         /// <returns>
         /// The parent, or null if the logical is unparented or its parent is not of type <typeparamref name="T"/>.
         /// </returns>
-        public static T GetLogicalParent<T>(this ILogical logical) where T : class
+        public static T? GetLogicalParent<T>(this ILogical logical) where T : class
         {
             return logical.LogicalParent as T;
         }
@@ -165,7 +165,7 @@ namespace Avalonia.LogicalTree
         /// <returns>The logical siblings.</returns>
         public static IEnumerable<ILogical> GetLogicalSiblings(this ILogical logical)
         {
-            ILogical parent = logical.LogicalParent;
+            var parent = logical.LogicalParent;
 
             if (parent != null)
             {
@@ -187,7 +187,7 @@ namespace Avalonia.LogicalTree
         /// </returns>
         public static bool IsLogicalAncestorOf(this ILogical logical, ILogical target)
         {
-            ILogical current = target?.LogicalParent;
+            var current = target?.LogicalParent;
 
             while (current != null)
             {
@@ -202,7 +202,7 @@ namespace Avalonia.LogicalTree
             return false;
         }
 
-        private static T FindDescendantOfTypeCore<T>(ILogical logical) where T : class
+        private static T? FindDescendantOfTypeCore<T>(ILogical logical) where T : class
         {
             var logicalChildren = logical.LogicalChildren;
             var logicalChildrenCount = logicalChildren.Count;

src/Avalonia.Styling/LogicalTree/LogicalTreeAttachmentEventArgs.cs

@@ -19,11 +19,8 @@ namespace Avalonia.LogicalTree
             ILogical source,
             ILogical parent)
         {
-            Contract.Requires<ArgumentNullException>(root != null);
+            Root = root ?? throw new ArgumentNullException(nameof(root));
-            Contract.Requires<ArgumentNullException>(source != null);
+            Source = source ?? throw new ArgumentNullException(nameof(source));
-
-            Root = root;
-            Source = source;
             Parent = parent;
         }
 

src/Avalonia.Styling/StyledElement.cs

@@ -427,7 +427,7 @@ namespace Avalonia
 
                 if (_logicalRoot != null)
                 {
-                    var e = new LogicalTreeAttachmentEventArgs(_logicalRoot, this, old);
+                    var e = new LogicalTreeAttachmentEventArgs(_logicalRoot, this, old!);
                     OnDetachedFromLogicalTreeCore(e);
                 }
 
@@ -435,7 +435,7 @@ namespace Avalonia
 
                 if (newRoot is object)
                 {
-                    var e = new LogicalTreeAttachmentEventArgs(newRoot, this, parent);
+                    var e = new LogicalTreeAttachmentEventArgs(newRoot, this, parent!);
                     OnAttachedToLogicalTreeCore(e);
                 }
                 else if (parent is null)
@@ -495,21 +495,21 @@ namespace Avalonia
             DetachStylesFromThisAndDescendents(allStyles);
         }
 
-        protected virtual void LogicalChildrenCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
+        protected virtual void LogicalChildrenCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
         {
             switch (e.Action)
             {
                 case NotifyCollectionChangedAction.Add:
-                    SetLogicalParent(e.NewItems);
+                    SetLogicalParent(e.NewItems!);
                     break;
 
                 case NotifyCollectionChangedAction.Remove:
-                    ClearLogicalParent(e.OldItems);
+                    ClearLogicalParent(e.OldItems!);
                     break;
 
                 case NotifyCollectionChangedAction.Replace:
-                    ClearLogicalParent(e.OldItems);
+                    ClearLogicalParent(e.OldItems!);
-                    SetLogicalParent(e.NewItems);
+                    SetLogicalParent(e.NewItems!);
                     break;
 
                 case NotifyCollectionChangedAction.Reset:
@@ -729,7 +729,7 @@ namespace Avalonia
 
             for (var i = 0; i < count; i++)
             {
-                var logical = (ILogical) children[i];
+                var logical = (ILogical) children[i]!;
                 
                 if (logical.LogicalParent is null)
                 {
@@ -744,7 +744,7 @@ namespace Avalonia
 
             for (var i = 0; i < count; i++)
             {
-                var logical = (ILogical) children[i];
+                var logical = (ILogical) children[i]!;
                 
                 if (logical.LogicalParent == this)
                 {

src/Avalonia.Styling/Styling/Activators/NthChildActivator.cs

@@ -37,7 +37,7 @@ namespace Avalonia.Styling.Activators
             _provider.ChildIndexChanged -= ChildIndexChanged;
         }
 
-        private void ChildIndexChanged(object sender, ChildIndexChangedEventArgs e)
+        private void ChildIndexChanged(object? sender, ChildIndexChangedEventArgs e)
         {
             // Run matching again if:
             // 1. Selector is reversed, so other item insertion/deletion might affect total count without changing subscribed item index.

src/Avalonia.Styling/Styling/Activators/StyleClassActivator.cs

@@ -66,7 +66,7 @@ namespace Avalonia.Styling.Activators
             _classes.CollectionChanged -= ClassesChangedHandler;
         }
 
-        private void ClassesChanged(object sender, NotifyCollectionChangedEventArgs e)
+        private void ClassesChanged(object? sender, NotifyCollectionChangedEventArgs e)
         {
             if (e.Action != NotifyCollectionChangedAction.Move)
             {

src/Avalonia.Styling/Styling/ChildSelector.cs

@@ -6,7 +6,7 @@ namespace Avalonia.Styling
     internal class ChildSelector : Selector
     {
         private readonly Selector _parent;
-        private string _selectorString;
+        private string? _selectorString;
 
         public ChildSelector(Selector parent)
         {
@@ -25,7 +25,7 @@ namespace Avalonia.Styling
         public override bool IsCombinator => true;
 
         /// <inheritdoc/>
-        public override Type TargetType => null;
+        public override Type? TargetType => null;
 
         public override string ToString()
         {
@@ -64,6 +64,6 @@ namespace Avalonia.Styling
             }
         }
 
-        protected override Selector MovePrevious() => null;
+        protected override Selector? MovePrevious() => null;
     }
 }

src/Avalonia.Styling/Styling/OrSelector.cs

@@ -120,7 +120,7 @@ namespace Avalonia.Styling
                 }
                 else
                 {
-                    while (!result.IsAssignableFrom(selector.TargetType))
+                    while (result is not null && !result.IsAssignableFrom(selector.TargetType))
                     {
                         result = result.BaseType;
                     }

src/Avalonia.Styling/Styling/PropertyEqualsSelector.cs

@@ -53,11 +53,16 @@ namespace Avalonia.Styling
 
                 if (_property.IsAttached)
                 {
+                    builder.Append('(');
                     builder.Append(_property.OwnerType.Name);
                     builder.Append('.');
                 }
 
                 builder.Append(_property.Name);
+                if (_property.IsAttached)
+                {
+                    builder.Append(')');
+                }
                 builder.Append('=');
                 builder.Append(_value ?? string.Empty);
                 builder.Append(']');
@@ -104,7 +109,7 @@ namespace Avalonia.Styling
             var converter = TypeDescriptor.GetConverter(propertyType);
             if (converter?.CanConvertFrom(valueType) == true)
             {
-                return Equals(propertyValue, converter.ConvertFrom(null, CultureInfo.InvariantCulture, value));
+                return Equals(propertyValue, converter.ConvertFrom(null, CultureInfo.InvariantCulture, value!));
             }
 
             return false;

src/Avalonia.Styling/Styling/Selectors.cs

@@ -25,10 +25,14 @@ namespace Avalonia.Styling
         /// <param name="previous">The previous selector.</param>
         /// <param name="name">The name of the style class.</param>
         /// <returns>The selector.</returns>
-        public static Selector Class(this Selector previous, string name)
+        public static Selector Class(this Selector? previous, string name)
         {
-            Contract.Requires<ArgumentNullException>(name != null);
+            _ = name ?? throw new ArgumentNullException(nameof(name));
-            Contract.Requires<ArgumentException>(!string.IsNullOrWhiteSpace(name));
+
+            if (string.IsNullOrWhiteSpace(name))
+            {
+                throw new ArgumentException("Name may not be empty", nameof(name));
+            }
 
             var tac = previous as TypeNameAndClassSelector;
 
@@ -48,7 +52,7 @@ namespace Avalonia.Styling
         /// </summary>
         /// <param name="previous">The previous selector.</param>
         /// <returns>The selector.</returns>
-        public static Selector Descendant(this Selector previous)
+        public static Selector Descendant(this Selector? previous)
         {
             return new DescendantSelector(previous);
         }
@@ -59,9 +63,9 @@ namespace Avalonia.Styling
         /// <param name="previous">The previous selector.</param>
         /// <param name="type">The type.</param>
         /// <returns>The selector.</returns>
-        public static Selector Is(this Selector previous, Type type)
+        public static Selector Is(this Selector? previous, Type type)
         {
-            Contract.Requires<ArgumentNullException>(type != null);
+            _ = type ?? throw new ArgumentNullException(nameof(type));
 
             return TypeNameAndClassSelector.Is(previous, type);
         }
@@ -72,7 +76,7 @@ namespace Avalonia.Styling
         /// <typeparam name="T">The type.</typeparam>
         /// <param name="previous">The previous selector.</param>
         /// <returns>The selector.</returns>
-        public static Selector Is<T>(this Selector previous) where T : IStyleable
+        public static Selector Is<T>(this Selector? previous) where T : IStyleable
         {
             return previous.Is(typeof(T));
         }
@@ -83,10 +87,14 @@ namespace Avalonia.Styling
         /// <param name="previous">The previous selector.</param>
         /// <param name="name">The name.</param>
         /// <returns>The selector.</returns>
-        public static Selector Name(this Selector previous, string name)
+        public static Selector Name(this Selector? previous, string name)
         {
-            Contract.Requires<ArgumentNullException>(name != null);
+            _ = name ?? throw new ArgumentNullException(nameof(name));
-            Contract.Requires<ArgumentException>(!string.IsNullOrWhiteSpace(name));
+
+            if (string.IsNullOrWhiteSpace(name))
+            {
+                throw new ArgumentException("Name may not be empty", nameof(name));
+            }
 
             var tac = previous as TypeNameAndClassSelector;
 
@@ -107,7 +115,7 @@ namespace Avalonia.Styling
         /// <param name="previous">The previous selector.</param>
         /// <param name="argument">The selector to be not-ed.</param>
         /// <returns>The selector.</returns>
-        public static Selector Not(this Selector previous, Func<Selector, Selector> argument)
+        public static Selector Not(this Selector? previous, Func<Selector?, Selector> argument)
         {
             return new NotSelector(previous, argument(null));
         }
@@ -118,7 +126,7 @@ namespace Avalonia.Styling
         /// <param name="previous">The previous selector.</param>
         /// <param name="argument">The selector to be not-ed.</param>
         /// <returns>The selector.</returns>
-        public static Selector Not(this Selector previous, Selector argument)
+        public static Selector Not(this Selector? previous, Selector argument)
         {
             return new NotSelector(previous, argument);
         }
@@ -126,7 +134,7 @@ namespace Avalonia.Styling
         /// <inheritdoc cref="NthChildSelector"/>
         /// <inheritdoc cref="NthChildSelector(Selector?, int, int)"/>
         /// <returns>The selector.</returns>
-        public static Selector NthChild(this Selector previous, int step, int offset)
+        public static Selector NthChild(this Selector? previous, int step, int offset)
         {
             return new NthChildSelector(previous, step, offset);
         }
@@ -134,7 +142,7 @@ namespace Avalonia.Styling
         /// <inheritdoc cref="NthLastChildSelector"/>
         /// <inheritdoc cref="NthLastChildSelector(Selector?, int, int)"/>
         /// <returns>The selector.</returns>
-        public static Selector NthLastChild(this Selector previous, int step, int offset)
+        public static Selector NthLastChild(this Selector? previous, int step, int offset)
         {
             return new NthLastChildSelector(previous, step, offset);
         }
@@ -145,9 +153,9 @@ namespace Avalonia.Styling
         /// <param name="previous">The previous selector.</param>
         /// <param name="type">The type.</param>
         /// <returns>The selector.</returns>
-        public static Selector OfType(this Selector previous, Type type)
+        public static Selector OfType(this Selector? previous, Type type)
         {
-            Contract.Requires<ArgumentNullException>(type != null);
+            _ = type ?? throw new ArgumentNullException(nameof(type));
 
             return TypeNameAndClassSelector.OfType(previous, type);
         }
@@ -158,7 +166,7 @@ namespace Avalonia.Styling
         /// <typeparam name="T">The type.</typeparam>
         /// <param name="previous">The previous selector.</param>
         /// <returns>The selector.</returns>
-        public static Selector OfType<T>(this Selector previous) where T : IStyleable
+        public static Selector OfType<T>(this Selector? previous) where T : IStyleable
         {
             return previous.OfType(typeof(T));
         }
@@ -191,9 +199,9 @@ namespace Avalonia.Styling
         /// <param name="property">The property.</param>
         /// <param name="value">The property value.</param>
         /// <returns>The selector.</returns>
-        public static Selector PropertyEquals<T>(this Selector previous, AvaloniaProperty<T> property, object value)
+        public static Selector PropertyEquals<T>(this Selector? previous, AvaloniaProperty<T> property, object? value)
         {
-            Contract.Requires<ArgumentNullException>(property != null);
+            _ = property ?? throw new ArgumentNullException(nameof(property));
 
             return new PropertyEqualsSelector(previous, property, value);
         }
@@ -205,9 +213,9 @@ namespace Avalonia.Styling
         /// <param name="property">The property.</param>
         /// <param name="value">The property value.</param>
         /// <returns>The selector.</returns>
-        public static Selector PropertyEquals(this Selector previous, AvaloniaProperty property, object value)
+        public static Selector PropertyEquals(this Selector? previous, AvaloniaProperty property, object? value)
         {
-            Contract.Requires<ArgumentNullException>(property != null);
+            _ = property ?? throw new ArgumentNullException(nameof(property));
 
             return new PropertyEqualsSelector(previous, property, value);
         }

src/Avalonia.Styling/Styling/Styles.cs

@@ -262,7 +262,7 @@ namespace Avalonia.Styling
             }
         }
 
-        private void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
+        private void OnCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
         {
             static IReadOnlyList<T> ToReadOnlyList<T>(IList list)
             {
@@ -282,7 +282,7 @@ namespace Avalonia.Styling
             {
                 for (var i = 0; i < items.Count; ++i)
                 {
-                    var style = (IStyle)items[i];
+                    var style = (IStyle)items[i]!;
 
                     if (Owner is object && style is IResourceProvider resourceProvider)
                     {
@@ -299,7 +299,7 @@ namespace Avalonia.Styling
             {
                 for (var i = 0; i < items.Count; ++i)
                 {
-                    var style = (IStyle)items[i];
+                    var style = (IStyle)items[i]!;
 
                     if (Owner is object && style is IResourceProvider resourceProvider)
                     {
@@ -315,14 +315,14 @@ namespace Avalonia.Styling
             switch (e.Action)
             {
                 case NotifyCollectionChangedAction.Add:
-                    Add(e.NewItems);
+                    Add(e.NewItems!);
                     break;
                 case NotifyCollectionChangedAction.Remove:
-                    Remove(e.OldItems);
+                    Remove(e.OldItems!);
                     break;
                 case NotifyCollectionChangedAction.Replace:
-                    Remove(e.OldItems);
+                    Remove(e.OldItems!);
-                    Add(e.NewItems);
+                    Add(e.NewItems!);
                     break;
                 case NotifyCollectionChangedAction.Reset:
                     throw new InvalidOperationException("Reset should not be called on Styles.");

src/Avalonia.Styling/Styling/TemplateSelector.cs

@@ -5,7 +5,7 @@ namespace Avalonia.Styling
     internal class TemplateSelector : Selector
     {
         private readonly Selector _parent;
-        private string _selectorString;
+        private string? _selectorString;
 
         public TemplateSelector(Selector parent)
         {
@@ -24,7 +24,7 @@ namespace Avalonia.Styling
         public override bool IsCombinator => true;
 
         /// <inheritdoc/>
-        public override Type TargetType => null;
+        public override Type? TargetType => null;
 
         public override string ToString()
         {
@@ -48,6 +48,6 @@ namespace Avalonia.Styling
             return _parent.Match(templatedParent, subscribe);
         }
 
-        protected override Selector MovePrevious() => null;
+        protected override Selector? MovePrevious() => null;
     }
 }

src/Avalonia.Themes.Default/Avalonia.Themes.Default.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="..\Markup\Avalonia.Markup.Xaml\Avalonia.Markup.Xaml.csproj" />

src/Avalonia.Themes.Default/CalendarDatePicker.xaml

@@ -115,7 +115,11 @@
                  StaysOpen="False">
             <Calendar Name="PART_Calendar"
                       FirstDayOfWeek="{TemplateBinding FirstDayOfWeek}"
-                      IsTodayHighlighted="{TemplateBinding IsTodayHighlighted}"/>
+                      IsTodayHighlighted="{TemplateBinding IsTodayHighlighted}"
+                      SelectedDate="{TemplateBinding SelectedDate, Mode=TwoWay}"
+                      DisplayDate="{TemplateBinding DisplayDate}"
+                      DisplayDateStart="{TemplateBinding DisplayDateStart}"
+                      DisplayDateEnd="{TemplateBinding DisplayDateEnd}" />
           </Popup>
         </Grid>
       </ControlTemplate>

src/Avalonia.Themes.Fluent/Avalonia.Themes.Fluent.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="..\Markup\Avalonia.Markup.Xaml\Avalonia.Markup.Xaml.csproj" />

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

@@ -129,7 +129,11 @@
                  IsLightDismissEnabled="True">
             <Calendar Name="PART_Calendar"
                       FirstDayOfWeek="{TemplateBinding FirstDayOfWeek}"
-                      IsTodayHighlighted="{TemplateBinding IsTodayHighlighted}"/>
+                      IsTodayHighlighted="{TemplateBinding IsTodayHighlighted}"
+                      SelectedDate="{TemplateBinding SelectedDate, Mode=TwoWay}"
+                      DisplayDate="{TemplateBinding DisplayDate}"
+                      DisplayDateStart="{TemplateBinding DisplayDateStart}"
+                      DisplayDateEnd="{TemplateBinding DisplayDateEnd}" />
           </Popup>
         </Grid>
       </ControlTemplate>

src/Avalonia.Visuals/Animation/Animators/BaseBrushAnimator.cs

@@ -143,7 +143,7 @@ namespace Avalonia.Animation.Animators
                     if (!match(firstKeyType))
                         continue;
 
-                    animator = (IAnimator)Activator.CreateInstance(animatorType);
+                    animator = (IAnimator?)Activator.CreateInstance(animatorType);
                     if (animator != null)
                     {
                         animator.Property = Property;

src/Avalonia.Visuals/Animation/Animators/TransformAnimator.cs

@@ -11,10 +11,10 @@ namespace Avalonia.Animation.Animators
     /// </summary>
     public class TransformAnimator : Animator<double>
     {
-        DoubleAnimator _doubleAnimator;
+        DoubleAnimator? _doubleAnimator;
 
         /// <inheritdoc/>
-        public override IDisposable Apply(Animation animation, Animatable control, IClock clock, IObservable<bool> obsMatch, Action onComplete)
+        public override IDisposable? Apply(Animation animation, Animatable control, IClock clock, IObservable<bool> obsMatch, Action onComplete)
         {
             var ctrl = (Visual)control;
 

src/Avalonia.Visuals/Animation/CompositePageTransition.cs

@@ -37,7 +37,7 @@ namespace Avalonia.Animation
         public List<IPageTransition> PageTransitions { get; set; } = new List<IPageTransition>();
 
         /// <inheritdoc />
-        public Task Start(Visual from, Visual to, bool forward, CancellationToken cancellationToken)
+        public Task Start(Visual? from, Visual? to, bool forward, CancellationToken cancellationToken)
         {
             var transitionTasks = PageTransitions
                 .Select(transition => transition.Start(from, to, forward, cancellationToken))

src/Avalonia.Visuals/Animation/CrossFade.cs

@@ -100,7 +100,7 @@ namespace Avalonia.Animation
         }
 
         /// <inheritdoc cref="Start(Visual, Visual, CancellationToken)" />
-        public async Task Start(Visual from, Visual to, CancellationToken cancellationToken)
+        public async Task Start(Visual? from, Visual? to, CancellationToken cancellationToken)
         {
             if (cancellationToken.IsCancellationRequested)
             {
@@ -112,7 +112,7 @@ namespace Avalonia.Animation
             {
                 if (to != null)
                 {
-                    disposables.Add(to.SetValue(Visual.OpacityProperty, 0, Data.BindingPriority.Animation));
+                    disposables.Add(to.SetValue(Visual.OpacityProperty, 0, Data.BindingPriority.Animation)!);
                 }
 
                 if (from != null)
@@ -151,7 +151,7 @@ namespace Avalonia.Animation
         /// <returns>
         /// A <see cref="Task"/> that tracks the progress of the animation.
         /// </returns>
-        Task IPageTransition.Start(Visual from, Visual to, bool forward, CancellationToken cancellationToken)
+        Task IPageTransition.Start(Visual? from, Visual? to, bool forward, CancellationToken cancellationToken)
         {
             return Start(from, to, cancellationToken);
         }

src/Avalonia.Visuals/Animation/IPageTransition.cs

@@ -26,6 +26,6 @@ namespace Avalonia.Animation
         /// <returns>
         /// A <see cref="Task"/> that tracks the progress of the animation.
         /// </returns>
-        Task Start(Visual from, Visual to, bool forward, CancellationToken cancellationToken);
+        Task Start(Visual? from, Visual? to, bool forward, CancellationToken cancellationToken);
     }
 }

src/Avalonia.Visuals/Animation/PageSlide.cs

@@ -62,7 +62,7 @@ namespace Avalonia.Animation
         public Easing SlideOutEasing { get; set; } = new LinearEasing();
 
         /// <inheritdoc />
-        public async Task Start(Visual from, Visual to, bool forward, CancellationToken cancellationToken)
+        public async Task Start(Visual? from, Visual? to, bool forward, CancellationToken cancellationToken)
         {
             if (cancellationToken.IsCancellationRequested)
             {
@@ -155,17 +155,17 @@ namespace Avalonia.Animation
         /// <remarks>
         /// Any one of the parameters may be null, but not both.
         /// </remarks>
-        private static IVisual GetVisualParent(IVisual from, IVisual to)
+        private static IVisual GetVisualParent(IVisual? from, IVisual? to)
         {
-            var p1 = (from ?? to).VisualParent;
+            var p1 = (from ?? to)!.VisualParent;
-            var p2 = (to ?? from).VisualParent;
+            var p2 = (to ?? from)!.VisualParent;
 
             if (p1 != null && p2 != null && p1 != p2)
             {
                 throw new ArgumentException("Controls for PageSlide must have same parent.");
             }
 
-            return p1;
+            return p1 ?? throw new InvalidOperationException("Cannot determine visual parent.");
         }
     }
 }

src/Avalonia.Visuals/Animation/RenderLoopClock.cs

@@ -9,7 +9,7 @@ namespace Avalonia.Animation
     {
         protected override void Stop()
         {
-            AvaloniaLocator.Current.GetService<IRenderLoop>().Remove(this);
+            AvaloniaLocator.Current.GetRequiredService<IRenderLoop>().Remove(this);
         }
 
         bool IRenderLoopTask.NeedsUpdate => HasSubscriptions;

src/Avalonia.Visuals/ApiCompatBaseline.txt

@@ -5,6 +5,8 @@ InterfacesShouldHaveSameMembers : Interface member 'public System.Threading.Task
 MembersMustExist : Member 'public System.Threading.Tasks.Task Avalonia.Animation.IPageTransition.Start(Avalonia.Visual, Avalonia.Visual, System.Boolean)' does not exist in the implementation but it does exist in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public System.Threading.Tasks.Task Avalonia.Animation.IPageTransition.Start(Avalonia.Visual, Avalonia.Visual, System.Boolean, System.Threading.CancellationToken)' is present in the implementation but not in the contract.
 MembersMustExist : Member 'public System.Threading.Tasks.Task Avalonia.Animation.PageSlide.Start(Avalonia.Visual, Avalonia.Visual, System.Boolean)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public void Avalonia.Media.GlyphRun..ctor()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public void Avalonia.Media.GlyphRun.GlyphTypeface.set(Avalonia.Media.GlyphTypeface)' does not exist in the implementation but it does exist in the contract.
 TypeCannotChangeClassification : Type 'Avalonia.Media.Immutable.ImmutableSolidColorBrush' is a 'class' in the implementation but is a 'struct' in the contract.
 MembersMustExist : Member 'public void Avalonia.Media.TextFormatting.DrawableTextRun.Draw(Avalonia.Media.DrawingContext)' does not exist in the implementation but it does exist in the contract.
 CannotAddAbstractMembers : Member 'public void Avalonia.Media.TextFormatting.DrawableTextRun.Draw(Avalonia.Media.DrawingContext, Avalonia.Point)' is abstract in the implementation but is missing in the contract.
@@ -77,4 +79,4 @@ InterfacesShouldHaveSameMembers : Interface member 'public Avalonia.Platform.IWr
 InterfacesShouldHaveSameMembers : Interface member 'public Avalonia.Platform.IWriteableBitmapImpl Avalonia.Platform.IPlatformRenderInterface.LoadWriteableBitmap(System.String)' is present in the implementation but not in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public Avalonia.Platform.IWriteableBitmapImpl Avalonia.Platform.IPlatformRenderInterface.LoadWriteableBitmapToHeight(System.IO.Stream, System.Int32, Avalonia.Visuals.Media.Imaging.BitmapInterpolationMode)' is present in the implementation but not in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public Avalonia.Platform.IWriteableBitmapImpl Avalonia.Platform.IPlatformRenderInterface.LoadWriteableBitmapToWidth(System.IO.Stream, System.Int32, Avalonia.Visuals.Media.Imaging.BitmapInterpolationMode)' is present in the implementation but not in the contract.
-Total Issues: 78
+Total Issues: 79

src/Avalonia.Visuals/Avalonia.Visuals.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
     <RootNamespace>Avalonia</RootNamespace>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
@@ -15,4 +15,5 @@
   <Import Project="..\..\build\Rx.props" />
   <Import Project="..\..\build\System.Memory.props" />
   <Import Project="..\..\build\ApiDiff.props" />
+  <Import Project="..\..\build\NullableEnable.props" />
 </Project>

src/Avalonia.Visuals/CornerRadius.cs

@@ -91,7 +91,7 @@ namespace Avalonia
         /// </summary>
         /// <param name="obj">The Object to compare against.</param>
         /// <returns>True if the Object is equal to this corner radius; False otherwise.</returns>
-        public override bool Equals(object obj) => obj is CornerRadius other && Equals(other);
+        public override bool Equals(object? obj) => obj is CornerRadius other && Equals(other);
 
         public override int GetHashCode()
         {