Merge branch 'master' into feature/add-option-to-disable-app-nap

samples/ControlCatalog/Pages/CustomDrawingExampleControl.cs

@@ -59,10 +59,12 @@ namespace ControlCatalog.Pages
 
             };
             StreamGeometry sg = new StreamGeometry();
-            var cntx = sg.Open();
-            cntx.BeginFigure(new Point(-25.0d, -10.0d), false);
-            cntx.ArcTo(new Point(25.0d, -10.0d), new Size(10.0d, 10.0d), 0.0d, false, SweepDirection.Clockwise);
-            cntx.EndFigure(true);
+            using (var cntx = sg.Open())
+            {
+                cntx.BeginFigure(new Point(-25.0d, -10.0d), false);
+                cntx.ArcTo(new Point(25.0d, -10.0d), new Size(10.0d, 10.0d), 0.0d, false, SweepDirection.Clockwise);
+                cntx.EndFigure(true);
+            }
             _smileGeometry = sg.Clone();
         }
 

samples/interop/WindowsInteropTest/Program.cs

@@ -1,5 +1,4 @@
 using System;
-using Avalonia.Controls;
 using ControlCatalog;
 using Avalonia;
 
@@ -15,7 +14,15 @@ namespace WindowsInteropTest
         {
             System.Windows.Forms.Application.EnableVisualStyles();
             System.Windows.Forms.Application.SetCompatibleTextRenderingDefault(false);
-            AppBuilder.Configure<App>().UseWin32().UseDirect2D1().SetupWithoutStarting();
+            AppBuilder.Configure<App>()
+                .UseWin32()
+                .UseDirect2D1()
+                .With(new Win32PlatformOptions
+                {
+                    UseWindowsUIComposition = false,
+                    ShouldRenderOnUIThread = true // necessary for WPF
+                })
+                .SetupWithoutStarting();
             System.Windows.Forms.Application.Run(new SelectorForm());
         }
     }

samples/interop/WindowsInteropTest/WindowsInteropTest.csproj

@@ -2,7 +2,7 @@
   <PropertyGroup>
     <OutputType>WinExe</OutputType>
     <TargetFramework>net461</TargetFramework>
-
+    <PlatformTarget>x64</PlatformTarget>
     <UseWPF>true</UseWPF>
     <UseWindowsForms>true</UseWindowsForms>
   </PropertyGroup>
@@ -10,9 +10,6 @@
   <ItemGroup>
     <ProjectReference Include="..\..\..\src\Avalonia.Diagnostics\Avalonia.Diagnostics.csproj" />
     <ProjectReference Include="..\..\..\src\Windows\Avalonia.Win32.Interop\Avalonia.Win32.Interop.csproj" />
-    <ProjectReference Include="..\..\ControlCatalog\ControlCatalog.csproj">
-      <Project>{d0a739b9-3c68-4ba6-a328-41606954b6bd}</Project>
-      <Name>ControlCatalog</Name>
-    </ProjectReference>
+    <ProjectReference Include="..\..\ControlCatalog\ControlCatalog.csproj" />
   </ItemGroup>
 </Project>

src/Avalonia.Base/AvaloniaObject.cs

@@ -277,8 +277,8 @@ namespace Avalonia
         /// <param name="property">The property.</param>
         /// <returns>True if the property is set, otherwise false.</returns>
         /// <remarks>
-        /// Checks whether a value is assigned to the property, or that there is a binding to the
-        /// property that is producing a value other than <see cref="AvaloniaProperty.UnsetValue"/>.
+        /// Returns true if <paramref name="property"/> is a styled property which has a value
+        /// assigned to it or a binding targeting it; otherwise false.
         /// </remarks>
         public bool IsSet(AvaloniaProperty property)
         {

src/Avalonia.Base/PropertyStore/BindingEntryBase.cs

@@ -16,6 +16,8 @@ namespace Avalonia.PropertyStore
         private IDisposable? _subscription;
         private bool _hasValue;
         private TValue? _value;
+        private TValue? _defaultValue;
+        private bool _isDefaultValueInitialized;
 
         protected BindingEntryBase(
             ValueFrame frame,
@@ -89,6 +91,7 @@ namespace Avalonia.PropertyStore
 
         protected abstract BindingValue<TValue> ConvertAndValidate(TSource value);
         protected abstract BindingValue<TValue> ConvertAndValidate(BindingValue<TSource> value);
+        protected abstract TValue GetDefaultValue(Type ownerType);
 
         protected virtual void Start(bool produceValue)
         {
@@ -104,17 +107,6 @@ namespace Avalonia.PropertyStore
             };
         }
 
-        private void ClearValue()
-        {
-            if (_hasValue)
-            {
-                _hasValue = false;
-                _value = default;
-                if (_subscription is not null)
-                    Frame.Owner?.OnBindingValueCleared(Property, Frame.Priority);
-            }
-        }
-
         private void SetValue(BindingValue<TValue> value)
         {
             static void Execute(BindingEntryBase<TValue, TSource> instance, BindingValue<TValue> value)
@@ -124,24 +116,20 @@ namespace Avalonia.PropertyStore
 
                 LoggingUtils.LogIfNecessary(instance.Frame.Owner.Owner, instance.Property, value);
 
-                if (value.HasValue)
-                {
-                    if (!instance._hasValue || !EqualityComparer<TValue>.Default.Equals(instance._value, value.Value))
-                    {
-                        instance._value = value.Value;
-                        instance._hasValue = true;
-                        if (instance._subscription is not null && instance._subscription != s_creatingQuiet)
-                            instance.Frame.Owner?.OnBindingValueChanged(instance, instance.Frame.Priority);
-                    }
-                }
-                else if (value.Type != BindingValueType.DoNothing)
+                var effectiveValue = value.HasValue ? value.Value : instance.GetCachedDefaultValue();
+
+                if (!instance._hasValue || !EqualityComparer<TValue>.Default.Equals(instance._value, effectiveValue))
                 {
-                    instance.ClearValue();
+                    instance._value = effectiveValue;
+                    instance._hasValue = true;
                     if (instance._subscription is not null && instance._subscription != s_creatingQuiet)
-                        instance.Frame.Owner?.OnBindingValueCleared(instance.Property, instance.Frame.Priority);
+                        instance.Frame.Owner?.OnBindingValueChanged(instance, instance.Frame.Priority);
                 }
             }
 
+            if (value.Type == BindingValueType.DoNothing)
+                return;
+
             if (Dispatcher.UIThread.CheckAccess())
             {
                 Execute(this, value);
@@ -161,5 +149,16 @@ namespace Avalonia.PropertyStore
             _subscription = null;
             Frame.OnBindingCompleted(this);
         }
+
+        private TValue GetCachedDefaultValue()
+        {
+            if (!_isDefaultValueInitialized)
+            {
+                _defaultValue = GetDefaultValue(Frame.Owner!.Owner.GetType());
+                _isDefaultValueInitialized = true;
+            }
+
+            return _defaultValue!;
+        }
     }
 }

src/Avalonia.Base/PropertyStore/LocalValueBindingObserver.cs

@@ -10,6 +10,8 @@ namespace Avalonia.PropertyStore
     {
         private readonly ValueStore _owner;
         private IDisposable? _subscription;
+        private T? _defaultValue;
+        private bool _isDefaultValueInitialized;
 
         public LocalValueBindingObserver(ValueStore owner, StyledProperty<T> property)
         {
@@ -41,26 +43,28 @@ namespace Avalonia.PropertyStore
 
         public void OnNext(T value)
         {
-            static void Execute(ValueStore owner, StyledProperty<T> property, T value)
+            static void Execute(LocalValueBindingObserver<T> instance, T value)
             {
-                if (property.ValidateValue?.Invoke(value) != false)
-                    owner.SetValue(property, value, BindingPriority.LocalValue);
-                else
-                    owner.ClearLocalValue(property);
+                var owner = instance._owner;
+                var property = instance.Property;
+
+                if (property.ValidateValue?.Invoke(value) == false)
+                    value = instance.GetCachedDefaultValue();
+
+                owner.SetValue(property, value, BindingPriority.LocalValue);
             }
 
             if (Dispatcher.UIThread.CheckAccess())
             {
-                Execute(_owner, Property, value);
+                Execute(this, value);
             }
             else
             {
                 // To avoid allocating closure in the outer scope we need to capture variables
                 // locally. This allows us to skip most of the allocations when on UI thread.
-                var instance = _owner;
-                var property = Property;
+                var instance = this;
                 var newValue = value;
-                Dispatcher.UIThread.Post(() => Execute(instance, property, newValue));
+                Dispatcher.UIThread.Post(() => Execute(instance, newValue));
             }
         }
 
@@ -74,11 +78,21 @@ namespace Avalonia.PropertyStore
                 LoggingUtils.LogIfNecessary(owner.Owner, property, value);
 
                 if (value.HasValue)
-                    owner.SetValue(property, value.Value, BindingPriority.LocalValue);
-                else if (value.Type != BindingValueType.DataValidationError)
-                    owner.ClearLocalValue(property);
+                {
+                    var effectiveValue = value.Value;
+                    if (property.ValidateValue?.Invoke(effectiveValue) == false)
+                        effectiveValue = instance.GetCachedDefaultValue();
+                    owner.SetValue(property, effectiveValue, BindingPriority.LocalValue);
+                }
+                else
+                {
+                    owner.SetValue(property, instance.GetCachedDefaultValue(), BindingPriority.LocalValue);
+                }
             }
 
+            if (value.Type is BindingValueType.DoNothing or BindingValueType.DataValidationError)
+                return;
+
             if (Dispatcher.UIThread.CheckAccess())
             {
                 Execute(this, value);
@@ -92,5 +106,16 @@ namespace Avalonia.PropertyStore
                 Dispatcher.UIThread.Post(() => Execute(instance, newValue));
             }
         }
+
+        private T GetCachedDefaultValue()
+        {
+            if (!_isDefaultValueInitialized)
+            {
+                _defaultValue = Property.GetDefaultValue(_owner.Owner.GetType());
+                _isDefaultValueInitialized = true;
+            }
+
+            return _defaultValue!;
+        }
     }
 }

src/Avalonia.Base/PropertyStore/LocalValueUntypedBindingObserver.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Security.Cryptography;
 using Avalonia.Data;
 using Avalonia.Threading;
 
@@ -10,6 +9,8 @@ namespace Avalonia.PropertyStore
     {
         private readonly ValueStore _owner;
         private IDisposable? _subscription;
+        private T? _defaultValue;
+        private bool _isDefaultValueInitialized;
 
         public LocalValueUntypedBindingObserver(ValueStore owner, StyledProperty<T> property)
         {
@@ -49,11 +50,7 @@ namespace Avalonia.PropertyStore
 
                 if (value == AvaloniaProperty.UnsetValue)
                 {
-                    owner.ClearLocalValue(property);
-                }
-                else if (value == BindingOperations.DoNothing)
-                {
-                    // Do nothing!
+                    owner.SetValue(property, instance.GetCachedDefaultValue(), BindingPriority.LocalValue);
                 }
                 else if (UntypedValueUtils.TryConvertAndValidate(property, value, out var typedValue))
                 {
@@ -61,11 +58,14 @@ namespace Avalonia.PropertyStore
                 }
                 else
                 {
-                    owner.ClearLocalValue(property);
+                    owner.SetValue(property, instance.GetCachedDefaultValue(), BindingPriority.LocalValue);
                     LoggingUtils.LogInvalidValue(owner.Owner, property, typeof(T), value);
                 }
             }
 
+            if (value == BindingOperations.DoNothing)
+                return;
+
             if (Dispatcher.UIThread.CheckAccess())
             {
                 Execute(this, value);
@@ -79,5 +79,16 @@ namespace Avalonia.PropertyStore
                 Dispatcher.UIThread.Post(() => Execute(instance, newValue));
             }
         }
+
+        private T GetCachedDefaultValue()
+        {
+            if (!_isDefaultValueInitialized)
+            {
+                _defaultValue = Property.GetDefaultValue(_owner.Owner.GetType());
+                _isDefaultValueInitialized = true;
+            }
+
+            return _defaultValue!;
+        }
     }
 }

src/Avalonia.Base/PropertyStore/SourceUntypedBindingEntry.cs

@@ -31,5 +31,7 @@ namespace Avalonia.PropertyStore
         {
             throw new NotSupportedException();
         }
+
+        protected override TTarget GetDefaultValue(Type ownerType) => Property.GetDefaultValue(ownerType);
     }
 }

src/Avalonia.Base/PropertyStore/TypedBindingEntry.cs

@@ -48,5 +48,7 @@ namespace Avalonia.PropertyStore
             
             return value;
         }
+
+        protected override T GetDefaultValue(Type ownerType) => Property.GetDefaultValue(ownerType);
     }
 }

src/Avalonia.Base/PropertyStore/UntypedBindingEntry.cs

@@ -29,5 +29,10 @@ namespace Avalonia.PropertyStore
         {
             throw new NotSupportedException();
         }
+
+        protected override object? GetDefaultValue(Type ownerType)
+        {
+            return ((IStyledPropertyMetadata)Property.GetMetadata(ownerType)).DefaultValue;
+        }
     }
 }

src/Avalonia.Base/PropertyStore/ValueStore.cs

@@ -380,23 +380,6 @@ namespace Avalonia.PropertyStore
             }
         }
 
-        /// <summary>
-        /// Called by non-LocalValue binding entries to re-evaluate the effective value when the
-        /// binding produces an unset value.
-        /// </summary>
-        /// <param name="property">The bound property.</param>
-        /// <param name="priority">The priority of binding which produced a new value.</param>
-        public void OnBindingValueCleared(AvaloniaProperty property, BindingPriority priority)
-        {
-            Debug.Assert(priority != BindingPriority.LocalValue);
-
-            if (TryGetEffectiveValue(property, out var existing))
-            {
-                if (priority <= existing.Priority)
-                    ReevaluateEffectiveValue(property, existing);
-            }
-        }
-
         /// <summary>
         /// Called by a <see cref="ValueFrame"/> when its <see cref="ValueFrame.IsActive"/>
         /// state changes.

src/Avalonia.Base/Rendering/DefaultRenderTimer.cs

@@ -1,6 +1,4 @@
 using System;
-using System.Diagnostics;
-using System.Threading.Tasks;
 using Avalonia.Platform;
 
 namespace Avalonia.Rendering
@@ -59,7 +57,8 @@ namespace Avalonia.Rendering
             }
         }
 
-        public bool RunsInBackground => true;
+        /// <inheritdoc />
+        public virtual bool RunsInBackground => true;
 
         /// <summary>
         /// Starts the timer.

src/Avalonia.Base/Rendering/IRenderLoop.cs

@@ -27,7 +27,10 @@ namespace Avalonia.Rendering
         /// </summary>
         /// <param name="i">The update task.</param>
         void Remove(IRenderLoopTask i);
-        
+
+        /// <summary>
+        /// Indicates if the rendering is done on a non-UI thread.
+        /// </summary>
         bool RunsInBackground { get; }
     }
 }

src/Avalonia.Base/Rendering/RenderLoop.cs

@@ -87,6 +87,7 @@ namespace Avalonia.Rendering
             }
         }
 
+        /// <inheritdoc />
         public bool RunsInBackground => Timer.RunsInBackground;
 
         private void TimerTick(TimeSpan time)

src/Avalonia.Base/Rendering/UiThreadRenderTimer.cs

@@ -8,13 +8,20 @@ namespace Avalonia.Rendering
     /// <summary>
     /// Render timer that ticks on UI thread. Useful for debugging or bootstrapping on new platforms 
     /// </summary>
-    
     public class UiThreadRenderTimer : DefaultRenderTimer
     {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="UiThreadRenderTimer"/> class.
+        /// </summary>
+        /// <param name="framesPerSecond">The number of frames per second at which the loop should run.</param>
         public UiThreadRenderTimer(int framesPerSecond) : base(framesPerSecond)
         {
         }
 
+        /// <inheritdoc />
+        public override bool RunsInBackground => false;
+
+        /// <inheritdoc />
         protected override IDisposable StartCore(Action<TimeSpan> tick)
         {
             bool cancelled = false;

src/Avalonia.Controls/Border.cs

@@ -225,7 +225,7 @@ namespace Avalonia.Controls
         /// Renders the control.
         /// </summary>
         /// <param name="context">The drawing context.</param>
-        public override void Render(DrawingContext context)
+        public sealed override void Render(DrawingContext context)
         {
             _borderRenderHelper.Render(context, Bounds.Size, LayoutThickness, CornerRadius, Background, BorderBrush,
                 BoxShadow, BorderDashOffset, BorderLineCap, BorderLineJoin, BorderDashArray);

src/Avalonia.Controls/ExperimentalAcrylicBorder.cs

@@ -80,7 +80,7 @@ namespace Avalonia.Controls
             _subscription?.Dispose();
         }
 
-        public override void Render(DrawingContext context)
+        public sealed override void Render(DrawingContext context)
         {
             if (context.PlatformImpl is IDrawingContextWithAcrylicLikeSupport idc)
             {

src/Avalonia.Controls/Grid.cs

@@ -3256,7 +3256,7 @@ namespace Avalonia.Controls
             /// <summary>
             /// UpdateRenderBounds.
             /// </summary>
-            public override void Render(DrawingContext drawingContext)
+            public sealed override void Render(DrawingContext drawingContext)
             {
                 var grid = this.GetVisualParent<Grid>();
 

src/Avalonia.Controls/Image.cs

@@ -73,7 +73,7 @@ namespace Avalonia.Controls
         /// Renders the control.
         /// </summary>
         /// <param name="context">The drawing context.</param>
-        public override void Render(DrawingContext context)
+        public sealed override void Render(DrawingContext context)
         {
             var source = Source;
 

src/Avalonia.Controls/Panel.cs

@@ -68,7 +68,7 @@ namespace Avalonia.Controls
         /// Renders the visual to a <see cref="DrawingContext"/>.
         /// </summary>
         /// <param name="context">The drawing context.</param>
-        public override void Render(DrawingContext context)
+        public sealed override void Render(DrawingContext context)
         {
             var background = Background;
             if (background != null)

src/Avalonia.Controls/Presenters/ContentPresenter.cs

@@ -534,7 +534,7 @@ namespace Avalonia.Controls.Presenters
         }
 
         /// <inheritdoc/>
-        public override void Render(DrawingContext context)
+        public sealed override void Render(DrawingContext context)
         {
             _borderRenderer.Render(context, Bounds.Size, LayoutThickness, CornerRadius, Background, BorderBrush,
                 BoxShadow);

src/Avalonia.Controls/Presenters/TextPresenter.cs

@@ -388,7 +388,7 @@ namespace Avalonia.Controls.Presenters
             TextLayout.Draw(context, new Point(left, top));
         }
 
-        public override void Render(DrawingContext context)
+        public sealed override void Render(DrawingContext context)
         {
             var selectionStart = SelectionStart;
             var selectionEnd = SelectionEnd;

src/Avalonia.Controls/Primitives/AccessText.cs

@@ -60,10 +60,9 @@ namespace Avalonia.Controls.Primitives
         /// Renders the <see cref="AccessText"/> to a drawing context.
         /// </summary>
         /// <param name="context">The drawing context.</param>
-        public override void Render(DrawingContext context)
+        protected internal override void RenderCore(DrawingContext context)
         {
-            base.Render(context);
-
+            base.RenderCore(context);
             int underscore = Text?.IndexOf('_') ?? -1;
 
             if (underscore != -1 && ShowAccessKey)

src/Avalonia.Controls/Remote/RemoteWidget.cs

@@ -69,7 +69,7 @@ namespace Avalonia.Controls.Remote
             base.ArrangeCore(finalRect);
         }
 
-        public override void Render(DrawingContext context)
+        public sealed override void Render(DrawingContext context)
         {
             if (_lastFrame != null && _lastFrame.Width != 0 && _lastFrame.Height != 0)
             {

src/Avalonia.Controls/Shapes/Shape.cs

@@ -193,7 +193,7 @@ namespace Avalonia.Controls.Shapes
             set { SetValue(StrokeJoinProperty, value); }
         }
 
-        public override void Render(DrawingContext context)
+        public sealed override void Render(DrawingContext context)
         {
             var geometry = RenderedGeometry;
 

src/Avalonia.Controls/TextBlock.cs

@@ -549,7 +549,13 @@ namespace Avalonia.Controls
         /// Renders the <see cref="TextBlock"/> to a drawing context.
         /// </summary>
         /// <param name="context">The drawing context.</param>
-        public override void Render(DrawingContext context)
+        public sealed override void Render(DrawingContext context)
+        {
+            RenderCore(context);
+        }
+
+        // Workaround to seal Render method, we need to make so because AccessText was overriding Render method which is sealed now.
+        internal protected virtual void RenderCore(DrawingContext context)
         {
             var background = Background;
 

src/Avalonia.Controls/TickBar.cs

@@ -213,7 +213,7 @@ namespace Avalonia.Controls
         ///
         /// Brush that use to fill ticks is specified by Fill property.
         /// </summary>
-        public override void Render(DrawingContext dc)
+        public sealed override void Render(DrawingContext dc)
         {
             var size = new Size(Bounds.Width, Bounds.Height);
             var range = Maximum - Minimum;

src/Windows/Avalonia.Win32.Interop/Wpf/WpfTopLevelImpl.cs

@@ -45,13 +45,6 @@ namespace Avalonia.Win32.Interop.Wpf
                 ((FrameworkElement)PlatformImpl)?.InvalidateMeasure();
             }
 
-            protected override void HandleResized(Size clientSize, PlatformResizeReason reason)
-            {
-                ClientSize = clientSize;
-                LayoutManager.ExecuteLayoutPass();
-                Renderer?.Resized(clientSize);
-            }
-
             public Size AllocatedSize => ClientSize;
         }
 
@@ -223,7 +216,7 @@ namespace Avalonia.Win32.Interop.Wpf
                 (Key)e.Key,
                 GetModifiers(null)));
 
-        protected override void OnTextInput(TextCompositionEventArgs e) 
+        protected override void OnTextInput(TextCompositionEventArgs e)
             => _ttl.Input?.Invoke(new RawTextInputEventArgs(_keyboard, (uint) e.Timestamp, _inputRoot, e.Text));
 
         void ITopLevelImpl.SetCursor(ICursorImpl cursor)

src/Windows/Avalonia.Win32/TrayIconImpl.cs

@@ -81,19 +81,18 @@ namespace Avalonia.Win32
 
         private void UpdateIcon(bool remove = false)
         {
-            var iconData = new NOTIFYICONDATA()
+            var iconData = new NOTIFYICONDATA
             {
                 hWnd = Win32Platform.Instance.Handle,
-                uID = _uniqueId,
-                uFlags = NIF.TIP | NIF.MESSAGE,
-                uCallbackMessage = (int)CustomWindowsMessage.WM_TRAYMOUSE,
-                hIcon = _icon?.HIcon ?? s_emptyIcon,
-                szTip = _tooltipText ?? ""
+                uID = _uniqueId
             };
 
             if (!remove)
             {
-                iconData.uFlags |= NIF.ICON;
+                iconData.uFlags = NIF.TIP | NIF.MESSAGE | NIF.ICON;
+                iconData.uCallbackMessage = (int)CustomWindowsMessage.WM_TRAYMOUSE;
+                iconData.hIcon = _icon?.HIcon ?? s_emptyIcon;
+                iconData.szTip = _tooltipText ?? "";
 
                 if (!_iconAdded)
                 {
@@ -107,6 +106,7 @@ namespace Avalonia.Win32
             }
             else
             {
+                iconData.uFlags = 0;
                 Shell_NotifyIcon(NIM.DELETE, iconData);
                 _iconAdded = false;
             }

src/Windows/Avalonia.Win32/Win32Platform.cs

@@ -6,12 +6,10 @@ using System.IO;
 using Avalonia.Reactive;
 using System.Runtime.InteropServices;
 using System.Threading;
-using Avalonia.Controls;
 using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Controls.Platform;
 using Avalonia.Input;
 using Avalonia.Input.Platform;
-using Avalonia.Media;
 using Avalonia.OpenGL;
 using Avalonia.Platform;
 using Avalonia.Rendering;
@@ -20,7 +18,6 @@ using Avalonia.Threading;
 using Avalonia.Utilities;
 using Avalonia.Win32.Input;
 using Avalonia.Win32.Interop;
-using Avalonia.Win32.WinRT;
 using static Avalonia.Win32.Interop.UnmanagedMethods;
 
 namespace Avalonia
@@ -68,6 +65,7 @@ namespace Avalonia
 
         /// <summary>
         /// Render Avalonia to a Texture inside the Windows.UI.Composition tree.
+        /// This setting is true by default.
         /// </summary>
         /// <remarks>
         /// Supported on Windows 10 build 16299 and above. Ignored on other versions.
@@ -88,9 +86,19 @@ namespace Avalonia
         /// This is only recommended if low input latency is desirable, and there is no need for the transparency
         /// and stylings / blurrings offered by <see cref="UseWindowsUIComposition"/><br/>
         /// This is mutually exclusive with 
-        /// <see cref="UseWindowsUIComposition"/> which if active will override this setting. 
+        /// <see cref="UseWindowsUIComposition"/> which if active will override this setting.
+        /// This setting is false by default.
         /// </summary>
-        public bool UseLowLatencyDxgiSwapChain { get; set; } = false;
+        public bool UseLowLatencyDxgiSwapChain { get; set; }
+
+        /// <summary>
+        /// Render directly on the UI thread instead of using a dedicated render thread.
+        /// Only applicable if both <see cref="UseWindowsUIComposition"/> and <see cref="UseLowLatencyDxgiSwapChain"/>
+        /// are false.
+        /// This setting is only recommended for interop with systems that must render on the UI thread, such as WPF.
+        /// This setting is false by default.
+        /// </summary>
+        public bool ShouldRenderOnUIThread { get; set; }
         
         /// <summary>
         /// Provides a way to use a custom-implemented graphics context such as a custom ISkiaGpu
@@ -128,7 +136,7 @@ namespace Avalonia.Win32
 
         internal static bool UseOverlayPopups => Options.OverlayPopups;
         public static Win32PlatformOptions Options { get; private set; }
-        
+
         internal static Compositor Compositor { get; private set; }
 
         public static void Initialize()
@@ -139,6 +147,8 @@ namespace Avalonia.Win32
         public static void Initialize(Win32PlatformOptions options)
         {
             Options = options;
+            var renderTimer = options.ShouldRenderOnUIThread ? new UiThreadRenderTimer(60) : new DefaultRenderTimer(60);
+
             AvaloniaLocator.CurrentMutable
                 .Bind<IClipboard>().ToSingleton<ClipboardImpl>()
                 .Bind<ICursorFactory>().ToConstant(CursorFactory.Instance)
@@ -146,7 +156,7 @@ namespace Avalonia.Win32
                 .Bind<IPlatformSettings>().ToSingleton<Win32PlatformSettings>()
                 .Bind<IPlatformThreadingInterface>().ToConstant(s_instance)
                 .Bind<IRenderLoop>().ToConstant(new RenderLoop())
-                .Bind<IRenderTimer>().ToConstant(new DefaultRenderTimer(60))
+                .Bind<IRenderTimer>().ToConstant(renderTimer)
                 .Bind<IWindowingPlatform>().ToConstant(s_instance)
                 .Bind<PlatformHotkeyConfiguration>().ToConstant(new PlatformHotkeyConfiguration(KeyModifiers.Control)
                 {

tests/Avalonia.Base.UnitTests/AvaloniaObjectTests_Binding.cs

@@ -372,6 +372,20 @@ namespace Avalonia.Base.UnitTests
             Assert.Null(target.GetValue(property));
         }
 
+        [Fact]
+        public void LocalValue_Bind_Generic_To_ValueType_Accepts_UnsetValue()
+        {
+            var target = new Class1();
+            var source = new Subject<BindingValue<double>>();
+
+            target.Bind(Class1.QuxProperty, source);
+            source.OnNext(6.7);
+            source.OnNext(BindingValue<double>.Unset);
+
+            Assert.Equal(5.6, target.GetValue(Class1.QuxProperty));
+            Assert.True(target.IsSet(Class1.QuxProperty));
+        }
+
         [Fact]
         public void LocalValue_Bind_NonGeneric_To_ValueType_Accepts_UnsetValue()
         {
@@ -383,7 +397,7 @@ namespace Avalonia.Base.UnitTests
             source.OnNext(AvaloniaProperty.UnsetValue);
 
             Assert.Equal(5.6, target.GetValue(Class1.QuxProperty));
-            Assert.False(target.IsSet(Class1.QuxProperty));
+            Assert.True(target.IsSet(Class1.QuxProperty));
         }
 
         [Fact]
@@ -397,7 +411,7 @@ namespace Avalonia.Base.UnitTests
             source.OnNext(AvaloniaProperty.UnsetValue);
 
             Assert.Equal(5.6, target.GetValue(Class1.QuxProperty));
-            Assert.False(target.IsSet(Class1.QuxProperty));
+            Assert.True(target.IsSet(Class1.QuxProperty));
         }
 
         [Fact]
@@ -1285,6 +1299,24 @@ namespace Avalonia.Base.UnitTests
             subscription.Dispose();
         }
 
+        [Theory]
+        [InlineData(BindingPriority.LocalValue)]
+        [InlineData(BindingPriority.Style)]
+        public void Binding_Producing_UnsetValue_Does_Not_Cause_Unsubscribe(BindingPriority priority)
+        {
+            var target = new Class1();
+            var source = new Subject<BindingValue<string>>();
+            
+            target.Bind(Class1.FooProperty, source, priority);
+
+            source.OnNext("foo");
+            Assert.Equal("foo", target.GetValue(Class1.FooProperty));
+            source.OnNext(BindingValue<string>.Unset);
+            Assert.Equal("foodefault", target.GetValue(Class1.FooProperty));
+            source.OnNext("bar");
+            Assert.Equal("bar", target.GetValue(Class1.FooProperty));
+        }
+
         [Fact]
         public void Produces_Correct_Values_And_Base_Values_With_Multiple_Animation_Bindings()
         {

tests/Avalonia.Base.UnitTests/AvaloniaObjectTests_Validation.cs

@@ -66,7 +66,7 @@ namespace Avalonia.Base.UnitTests
         }
 
         [Fact]
-        public void Reverts_To_Lower_Priority_If_Style_Binding_Fails_Validation()
+        public void Reverts_To_DefaultValue_If_Style_Binding_Fails_Validation_2()
         {
             var target = new Class1();
             var source = new Subject<int>();
@@ -75,7 +75,21 @@ namespace Avalonia.Base.UnitTests
             target.Bind(Class1.FooProperty, source, BindingPriority.StyleTrigger);
             source.OnNext(150);
 
-            Assert.Equal(10, target.GetValue(Class1.FooProperty));
+            Assert.Equal(11, target.GetValue(Class1.FooProperty));
+        }
+
+        [Theory]
+        [InlineData(BindingPriority.LocalValue)]
+        [InlineData(BindingPriority.Style)]
+        public void Reverts_To_DefaultValue_If_Style_Binding_Fails_Validation_3(BindingPriority priority)
+        {
+            var target = new Class1();
+            var source = new Subject<BindingValue<int>>();
+
+            target.Bind(Class1.FooProperty, source, priority);
+            source.OnNext(150);
+
+            Assert.Equal(11, target.GetValue(Class1.FooProperty));
         }
 
         [Fact]

tests/Avalonia.Markup.Xaml.UnitTests/Xaml/ResourceDictionaryTests.cs

@@ -307,7 +307,30 @@ namespace Avalonia.Markup.Xaml.UnitTests.Xaml
                 Assert.True(buttonResources.ContainsDeferredKey("Red"));
             }
         }
-        
+
+        [Fact]
+        public void Dynamically_Changing_Referenced_Resources_Works_With_DynamicResource()
+        {
+            var xaml = @"
+<UserControl xmlns='https://github.com/avaloniaui'
+     xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'>
+  <UserControl.Resources>
+    <Color x:Key='color'>Red</Color>
+    <SolidColorBrush x:Key='brush' Color='{DynamicResource color}' />
+  </UserControl.Resources>
+</UserControl>";
+
+            var userControl = (UserControl)AvaloniaRuntimeXamlLoader.Load(xaml);
+
+            Assert.Equal(Colors.Red, ((ISolidColorBrush)userControl.FindResource("brush")!).Color);
+
+            userControl.Resources.Remove("color");
+            Assert.Equal(default, ((ISolidColorBrush)userControl.FindResource("brush")!).Color);
+
+            userControl.Resources.Add("color", Colors.Blue);
+            Assert.Equal(Colors.Blue, ((ISolidColorBrush)userControl.FindResource("brush")!).Color);
+        }
+
         private IDisposable StyledWindow(params (string, string)[] assets)
         {
             var services = TestServices.StyledWindow.With(