Merge branch 'master' into rndr4

4 years ago · 5d143a2cdf
250 changed files with 2251 additions and 1009 deletions
--- a/build/ApiCompatAttributeExcludeList.txt
+++ b/build/ApiCompatAttributeExcludeList.txt
@ -0,0 +1,2 @@
+T:Avalonia.Metadata.NotClientImplementableAttribute
+T:Avalonia.Metadata.UnstableAttribute
--- a/build/CoreLibraries.props
+++ b/build/CoreLibraries.props
@ -3,8 +3,6 @@
      <ProjectReference Include="$(MSBuildThisFileDirectory)/../src/Avalonia.Base/Avalonia.Base.csproj" />
      <ProjectReference Include="$(MSBuildThisFileDirectory)/../src/Avalonia.Controls/Avalonia.Controls.csproj" />
      <ProjectReference Include="$(MSBuildThisFileDirectory)/../src/Avalonia.DesignerSupport/Avalonia.DesignerSupport.csproj" />
-      <ProjectReference Include="$(MSBuildThisFileDirectory)/../src/Avalonia.Themes.Default/Avalonia.Themes.Default.csproj" />
-      <ProjectReference Include="$(MSBuildThisFileDirectory)/../src/Avalonia.Themes.Fluent/Avalonia.Themes.Fluent.csproj" />
      <ProjectReference Include="$(MSBuildThisFileDirectory)/../src/Avalonia.OpenGL/Avalonia.OpenGL.csproj" />
      <ProjectReference Include="$(MSBuildThisFileDirectory)/../src/Avalonia.Dialogs/Avalonia.Dialogs.csproj" />
      <ProjectReference Include="$(MSBuildThisFileDirectory)/../src/Markup/Avalonia.Markup/Avalonia.Markup.csproj" />
--- a/native/Avalonia.Native/src/OSX/AutoFitContentView.mm
+++ b/native/Avalonia.Native/src/OSX/AutoFitContentView.mm
@ -85,7 +85,7 @@
    _settingSize = true;
    [super setFrameSize:newSize];

-    auto window = static_cast<id <AvnWindowProtocol>>([self window]);
+    auto window = (id <AvnWindowProtocol>) [self window];

    // TODO get actual titlebar size

--- a/native/Avalonia.Native/src/OSX/AvnWindow.mm
+++ b/native/Avalonia.Native/src/OSX/AvnWindow.mm
@ -174,6 +174,11 @@
    [self setBackgroundColor: [NSColor clearColor]];

    _isExtended = false;
+
+#ifdef IS_NSPANEL
+    [self setCollectionBehavior:NSWindowCollectionBehaviorCanJoinAllSpaces|NSWindowCollectionBehaviorFullScreenAuxiliary];
+#endif
+
    return self;
 }

@ -194,6 +199,8 @@
    [self backingScaleFactor];
 }

+
+
 - (void)windowWillClose:(NSNotification *)notification
 {
    _closed = true;
@ -212,11 +219,14 @@
    // If the window has a child window being shown as a dialog then don't allow it to become the key window.
    for(NSWindow* uch in [self childWindows])
    {
-        auto ch = static_cast<id <AvnWindowProtocol>>(uch);
-        if(ch == nil)
+        if (![uch conformsToProtocol:@protocol(AvnWindowProtocol)])
+        {
            continue;
-        if (ch.isDialog)
-            return false;
+        }
+
+        id <AvnWindowProtocol> ch = (id <AvnWindowProtocol>) uch;
+
+        return !ch.isDialog;
    }

    return true;
@ -372,6 +382,11 @@

        if(cparent != nullptr)
        {
+            if(!cparent->IsShown())
+            {
+                return;
+            }
+
            if(cparent->WindowState() == Maximized)
            {
                cparent->SetWindowState(Normal);
--- a/native/Avalonia.Native/src/OSX/PopupImpl.mm
+++ b/native/Avalonia.Native/src/OSX/PopupImpl.mm
@ -50,11 +50,17 @@ protected:
            return S_OK;
        }
    }
+
 public:
    virtual bool ShouldTakeFocusOnShow() override
    {
        return false;
    }
+
+    virtual HRESULT Show(bool activate, bool isDialog) override
+    {
+        return WindowBaseImpl::Show(activate, true);
+    }
 };


--- a/native/Avalonia.Native/src/OSX/WindowBaseImpl.h
+++ b/native/Avalonia.Native/src/OSX/WindowBaseImpl.h
@ -60,6 +60,8 @@ BEGIN_INTERFACE_MAP()

    virtual HRESULT Show(bool activate, bool isDialog) override;

+    virtual bool IsShown ();
+
    virtual bool ShouldTakeFocusOnShow();

    virtual HRESULT Hide() override;
--- a/native/Avalonia.Native/src/OSX/WindowBaseImpl.mm
+++ b/native/Avalonia.Native/src/OSX/WindowBaseImpl.mm
@ -30,8 +30,8 @@ WindowBaseImpl::WindowBaseImpl(IAvnWindowBaseEvents *events, IAvnGlContext *gl)
    View = [[AvnView alloc] initWithParent:this];
    StandardContainer = [[AutoFitContentView new] initWithContent:View];

-    lastPositionSet.X = 100;
-    lastPositionSet.Y = 100;
+    lastPositionSet.X = -1;
+    lastPositionSet.Y = -1;
    lastSize = NSSize { 100, 100 };
    lastMaxSize = NSSize { CGFLOAT_MAX, CGFLOAT_MAX};
    lastMinSize = NSSize { 0, 0 };
@ -92,7 +92,11 @@ HRESULT WindowBaseImpl::Show(bool activate, bool isDialog) {
        CreateNSWindow(isDialog);
        InitialiseNSWindow();

-        SetPosition(lastPositionSet);
+        if(lastPositionSet.X >= 0 && lastPositionSet.Y >= 0)
+        {
+            SetPosition(lastPositionSet);
+        }
+
        UpdateStyle();

        [Window setTitle:_lastTitle];
@ -112,6 +116,11 @@ HRESULT WindowBaseImpl::Show(bool activate, bool isDialog) {
    }
 }

+bool WindowBaseImpl::IsShown ()
+{
+    return _shown;
+}
+
 bool WindowBaseImpl::ShouldTakeFocusOnShow() {
    return true;
 }
@ -191,9 +200,8 @@ HRESULT WindowBaseImpl::GetClientSize(AvnSize *ret) {
        if (ret == nullptr)
            return E_POINTER;

-        auto frame = [View frame];
-        ret->Width = frame.size.width;
-        ret->Height = frame.size.height;
+        ret->Width = lastSize.width;
+        ret->Height = lastSize.height;

        return S_OK;
    }
@ -206,9 +214,11 @@ HRESULT WindowBaseImpl::GetFrameSize(AvnSize *ret) {
        if (ret == nullptr)
            return E_POINTER;

-        auto frame = [Window frame];
-        ret->Width = frame.size.width;
-        ret->Height = frame.size.height;
+        if(Window != nullptr){
+            auto frame = [Window frame];
+            ret->Width = frame.size.width;
+            ret->Height = frame.size.height;
+        }

        return S_OK;
    }
@ -354,12 +364,17 @@ HRESULT WindowBaseImpl::GetPosition(AvnPoint *ret) {
            return E_POINTER;
        }

-        auto frame = [Window frame];
+        if(Window != nullptr) {
+            auto frame = [Window frame];

-        ret->X = frame.origin.x;
-        ret->Y = frame.origin.y + frame.size.height;
+            ret->X = frame.origin.x;
+            ret->Y = frame.origin.y + frame.size.height;

-        *ret = ConvertPointY(*ret);
+            *ret = ConvertPointY(*ret);
+        } else
+        {
+            *ret = lastPositionSet;
+        }

        return S_OK;
    }
@ -370,7 +385,10 @@ HRESULT WindowBaseImpl::SetPosition(AvnPoint point) {

    @autoreleasepool {
        lastPositionSet = point;
-        [Window setFrameTopLeftPoint:ToNSPoint(ConvertPointY(point))];
+
+        if(Window != nullptr) {
+            [Window setFrameTopLeftPoint:ToNSPoint(ConvertPointY(point))];
+        }

        return S_OK;
    }
@ -559,6 +577,7 @@ void WindowBaseImpl::InitialiseNSWindow() {
        [Window setContentMaxSize:lastMaxSize];

        [Window setOpaque:false];
+        [Window center];

        if (lastMenu != nullptr) {
            [GetWindowProtocol() applyMenu:lastMenu];
@ -576,7 +595,7 @@ id <AvnWindowProtocol> WindowBaseImpl::GetWindowProtocol() {
        return nullptr;
    }

-    return static_cast<id <AvnWindowProtocol>>(Window);
+    return (id <AvnWindowProtocol>) Window;
 }

 extern IAvnWindow* CreateAvnWindow(IAvnWindowEvents*events, IAvnGlContext* gl)
--- a/native/Avalonia.Native/src/OSX/WindowImpl.mm
+++ b/native/Avalonia.Native/src/OSX/WindowImpl.mm
@ -430,6 +430,9 @@ HRESULT WindowImpl::SetWindowState(AvnWindowState state) {
    START_COM_CALL;

    @autoreleasepool {
+        auto currentState = _actualWindowState;
+        _lastWindowState = state;
+
        if (Window == nullptr) {
            return S_OK;
        }
@ -440,9 +443,6 @@ HRESULT WindowImpl::SetWindowState(AvnWindowState state) {

        _inSetWindowState = true;

-        auto currentState = _actualWindowState;
-        _lastWindowState = state;
-
        if (currentState == Normal) {
            _preZoomSize = [Window frame];
        }
--- a/samples/BindingDemo/BindingDemo.csproj
+++ b/samples/BindingDemo/BindingDemo.csproj
@ -5,6 +5,7 @@
  </PropertyGroup>
  <ItemGroup>
    <ProjectReference Include="..\..\src\Avalonia.Diagnostics\Avalonia.Diagnostics.csproj" />
+    <ProjectReference Include="..\..\src\Avalonia.Themes.Default\Avalonia.Themes.Default.csproj" />
    <ProjectReference Include="..\..\src\Linux\Avalonia.LinuxFramebuffer\Avalonia.LinuxFramebuffer.csproj" />
    <ProjectReference Include="..\MiniMvvm\MiniMvvm.csproj" />
  </ItemGroup>
--- a/samples/ControlCatalog/ControlCatalog.csproj
+++ b/samples/ControlCatalog/ControlCatalog.csproj
@ -25,6 +25,8 @@
    <ProjectReference Include="..\..\packages\Avalonia\Avalonia.csproj" />
    <ProjectReference Include="..\..\src\Avalonia.Controls.ColorPicker\Avalonia.Controls.ColorPicker.csproj" />
    <ProjectReference Include="..\..\src\Avalonia.Controls.DataGrid\Avalonia.Controls.DataGrid.csproj" />
+    <ProjectReference Include="..\..\src\Avalonia.Themes.Default\Avalonia.Themes.Default.csproj" />
+    <ProjectReference Include="..\..\src\Avalonia.Themes.Fluent\Avalonia.Themes.Fluent.csproj" />
    <ProjectReference Include="..\MiniMvvm\MiniMvvm.csproj" />
    <ProjectReference Include="..\SampleControls\ControlSamples.csproj" />
  </ItemGroup>
--- a/samples/ControlCatalog/Pages/CalendarDatePickerPage.xaml
+++ b/samples/ControlCatalog/Pages/CalendarDatePickerPage.xaml
@ -10,8 +10,7 @@
                Margin="0,16,0,0"
                HorizontalAlignment="Center"
                Spacing="16">
-      <StackPanel Orientation="Vertical"
-                  Width="200">
+      <StackPanel Orientation="Vertical">
        <TextBlock Text="SelectedDateFormat: Short"/>
        <CalendarDatePicker Name="DatePicker1"
                    SelectedDateFormat="Short"
--- a/samples/ControlCatalog/Pages/TextBoxPage.xaml
+++ b/samples/ControlCatalog/Pages/TextBoxPage.xaml
@ -66,6 +66,12 @@
                 FontFamily="Comic Sans MS"
                 InputMethod.IsInputMethodEnabled="False"
                 Foreground="Red"/>
+        <TextBox AcceptsReturn="True" 
+                 TextWrapping="Wrap" 
+                 Width="200" 
+                 Height="125"
+                 LineHeight="32"
+                 Text="Multiline TextBox with TextWrapping and increased LineHeight.&#xD;&#xD;Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus magna. Cras in mi at felis aliquet congue. Ut a est eget ligula molestie gravida. Curabitur massa. Donec eleifend, libero at sagittis mollis, tellus est malesuada tellus, at luctus turpis elit sit amet quam. Vivamus pretium ornare est." />
      </StackPanel>
      <StackPanel Orientation="Vertical" Spacing="8" Margin="8">
        <Label Classes="h2" Target="{Binding #firstResMFont}">res_m fonts</Label>
--- a/samples/IntegrationTestApp/IntegrationTestApp.csproj
+++ b/samples/IntegrationTestApp/IntegrationTestApp.csproj
@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>WinExe</OutputType>
    <TargetFramework>net6.0</TargetFramework>
@ -18,6 +18,7 @@

  <ItemGroup>
    <ProjectReference Include="..\..\src\Avalonia.Diagnostics\Avalonia.Diagnostics.csproj" />
+    <ProjectReference Include="..\..\src\Avalonia.Themes.Fluent\Avalonia.Themes.Fluent.csproj" />
  </ItemGroup>
  
  <Import Project="..\..\build\BuildTargets.targets" />
--- a/samples/PlatformSanityChecks/PlatformSanityChecks.csproj
+++ b/samples/PlatformSanityChecks/PlatformSanityChecks.csproj
@ -7,6 +7,7 @@

  <ItemGroup>
    <ProjectReference Include="..\..\src\Avalonia.Desktop\Avalonia.Desktop.csproj" />
+    <ProjectReference Include="..\..\src\Avalonia.Themes.Default\Avalonia.Themes.Default.csproj" />
    <ProjectReference Include="..\..\src\Avalonia.X11\Avalonia.X11.csproj" />
  </ItemGroup>

--- a/samples/Previewer/Previewer.csproj
+++ b/samples/Previewer/Previewer.csproj
@ -9,6 +9,9 @@
    </Compile>
    <EmbeddedResource Include="**\*.xaml" />
  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\Avalonia.Themes.Default\Avalonia.Themes.Default.csproj" />
+  </ItemGroup>
  
  <Import Project="..\..\build\SampleApp.props" />
  <Import Project="..\..\build\ReferenceCoreLibraries.props" />
--- a/samples/RenderDemo/RenderDemo.csproj
+++ b/samples/RenderDemo/RenderDemo.csproj
@ -12,6 +12,7 @@
  </ItemGroup>
  <ItemGroup>
    <ProjectReference Include="..\..\src\Avalonia.Diagnostics\Avalonia.Diagnostics.csproj" />
+    <ProjectReference Include="..\..\src\Avalonia.Themes.Fluent\Avalonia.Themes.Fluent.csproj" />
    <ProjectReference Include="..\..\src\Linux\Avalonia.LinuxFramebuffer\Avalonia.LinuxFramebuffer.csproj" />
    <ProjectReference Include="..\MiniMvvm\MiniMvvm.csproj" />
    <ProjectReference Include="..\SampleControls\ControlSamples.csproj" />
--- a/samples/Sandbox/Sandbox.csproj
+++ b/samples/Sandbox/Sandbox.csproj
@ -10,6 +10,7 @@
    <ProjectReference Include="..\..\src\Avalonia.Diagnostics\Avalonia.Diagnostics.csproj" />
    <ProjectReference Include="..\..\src\Avalonia.Controls.ColorPicker\Avalonia.Controls.ColorPicker.csproj" />
    <ProjectReference Include="..\..\src\Avalonia.Controls.DataGrid\Avalonia.Controls.DataGrid.csproj" />
+    <ProjectReference Include="..\..\src\Avalonia.Themes.Fluent\Avalonia.Themes.Fluent.csproj" />
  </ItemGroup>
  
  <Import Project="..\..\build\SampleApp.props" />
--- a/samples/VirtualizationDemo/VirtualizationDemo.csproj
+++ b/samples/VirtualizationDemo/VirtualizationDemo.csproj
@ -5,6 +5,7 @@
  </PropertyGroup>
  <ItemGroup>
    <ProjectReference Include="..\..\src\Avalonia.Diagnostics\Avalonia.Diagnostics.csproj" />
+    <ProjectReference Include="..\..\src\Avalonia.Themes.Default\Avalonia.Themes.Default.csproj" />
    <ProjectReference Include="..\..\src\Linux\Avalonia.LinuxFramebuffer\Avalonia.LinuxFramebuffer.csproj" />
    <ProjectReference Include="..\MiniMvvm\MiniMvvm.csproj" />
  </ItemGroup>
--- a/samples/interop/Direct3DInteropSample/Direct3DInteropSample.csproj
+++ b/samples/interop/Direct3DInteropSample/Direct3DInteropSample.csproj
@ -22,6 +22,7 @@
      </EmbeddedResource>
    </ItemGroup>
    <ItemGroup>
+        <ProjectReference Include="..\..\..\src\Avalonia.Themes.Default\Avalonia.Themes.Default.csproj" />
        <ProjectReference Include="..\..\..\src\Windows\Avalonia.Direct2D1\Avalonia.Direct2D1.csproj" />
        <ProjectReference Include="..\..\..\src\Windows\Avalonia.Win32\Avalonia.Win32.csproj" />
        <ProjectReference Include="..\..\MiniMvvm\MiniMvvm.csproj" />
--- a/samples/interop/NativeEmbedSample/NativeEmbedSample.csproj
+++ b/samples/interop/NativeEmbedSample/NativeEmbedSample.csproj
@ -9,6 +9,7 @@

  <ItemGroup>
    <PackageReference Include="MonoMac.NetStandard" Version="0.0.4" />
+    <ProjectReference Include="..\..\..\src\Avalonia.Themes.Default\Avalonia.Themes.Default.csproj" />
    <ProjectReference Include="..\..\..\src\Windows\Avalonia.Direct2D1\Avalonia.Direct2D1.csproj" />
    <ProjectReference Include="..\..\..\src\Avalonia.Diagnostics\Avalonia.Diagnostics.csproj" />
    <ProjectReference Include="..\..\..\src\Avalonia.X11\Avalonia.X11.csproj" />
--- a/src/Avalonia.Base/Animation/IAnimation.cs
+++ b/src/Avalonia.Base/Animation/IAnimation.cs
@ -1,12 +1,14 @@
 using System;
 using System.Threading;
 using System.Threading.Tasks;
+using Avalonia.Metadata;

 namespace Avalonia.Animation
 {
    /// <summary>
    /// Interface for Animation objects
    /// </summary>
+    [NotClientImplementable]
    public interface IAnimation
    {
        /// <summary>
--- a/src/Avalonia.Base/Animation/IAnimationSetter.cs
+++ b/src/Avalonia.Base/Animation/IAnimationSetter.cs
@ -1,5 +1,8 @@
+using Avalonia.Metadata;
+
 namespace Avalonia.Animation
 {
+    [NotClientImplementable]
    public interface IAnimationSetter
    {
        AvaloniaProperty? Property { get; set; }
--- a/src/Avalonia.Base/Animation/IAnimator.cs
+++ b/src/Avalonia.Base/Animation/IAnimator.cs
@ -1,11 +1,13 @@
 using System;
 using System.Collections.Generic;
+using Avalonia.Metadata;

 namespace Avalonia.Animation
 {
    /// <summary>
    /// Interface for Animator objects
    /// </summary>
+    [NotClientImplementable]
    public interface IAnimator : IList<AnimatorKeyFrame>
    {
        /// <summary>
--- a/src/Avalonia.Base/Animation/IClock.cs
+++ b/src/Avalonia.Base/Animation/IClock.cs
@ -1,9 +1,9 @@
 using System;
-using System.Collections.Generic;
-using System.Text;
+using Avalonia.Metadata;

 namespace Avalonia.Animation
 {
+    [NotClientImplementable]
    public interface IClock : IObservable<TimeSpan>
    {
        PlayState PlayState { get; set; }
--- a/src/Avalonia.Base/Animation/IGlobalClock.cs
+++ b/src/Avalonia.Base/Animation/IGlobalClock.cs
@ -1,9 +1,8 @@
-using System;
-using System.Collections.Generic;
-using System.Text;
+using Avalonia.Metadata;

 namespace Avalonia.Animation
 {
+    [NotClientImplementable]
    public interface IGlobalClock : IClock
    {
    }
--- a/src/Avalonia.Base/Animation/ITransition.cs
+++ b/src/Avalonia.Base/Animation/ITransition.cs
@ -1,10 +1,12 @@
 using System;
+using Avalonia.Metadata;

 namespace Avalonia.Animation
 {
    /// <summary>
    /// Interface for Transition objects.
    /// </summary>
+    [NotClientImplementable]
    public interface ITransition
    {
        /// <summary>
--- a/src/Avalonia.Base/Collections/AvaloniaList.cs
+++ b/src/Avalonia.Base/Collections/AvaloniaList.cs
@ -394,7 +394,13 @@ namespace Avalonia.Collections
                        } while (en.MoveNext());

                        if (notificationItems is not null)
+                        {
                            NotifyAdd(notificationItems, index);
+                        }
+                        else
+                        {
+                            NotifyCountChanged();
+                        }
                    }
                }
            }
--- a/src/Avalonia.Base/Controls/INameScope.cs
+++ b/src/Avalonia.Base/Controls/INameScope.cs
@ -1,5 +1,4 @@
-using System;
-using System.Threading.Tasks;
+using Avalonia.Metadata;
 using Avalonia.Utilities;

 namespace Avalonia.Controls
@ -7,6 +6,7 @@ namespace Avalonia.Controls
    /// <summary>
    /// Defines a name scope.
    /// </summary>
+    [NotClientImplementable]
    public interface INameScope
    {
        /// <summary>
--- a/src/Avalonia.Base/Controls/IPseudoClasses.cs
+++ b/src/Avalonia.Base/Controls/IPseudoClasses.cs
@ -1,9 +1,11 @@
+using Avalonia.Metadata;

 namespace Avalonia.Controls
 {
    /// <summary>
    /// Exposes an interface for setting pseudoclasses on a <see cref="Classes"/> collection.
    /// </summary>
+    [NotClientImplementable]
    public interface IPseudoClasses
    {
        /// <summary>
--- a/src/Avalonia.Base/Controls/IResourceHost.cs
+++ b/src/Avalonia.Base/Controls/IResourceHost.cs
@ -1,6 +1,5 @@
 using System;
-
-#nullable enable
+using Avalonia.Metadata;

 namespace Avalonia.Controls
 {
@ -10,6 +9,7 @@ namespace Avalonia.Controls
    /// <remarks>
    /// This interface is implemented by <see cref="StyledElement"/> and `Application`.
    /// </remarks>
+    [NotClientImplementable]
    public interface IResourceHost : IResourceNode
    {
        /// <summary>
--- a/src/Avalonia.Base/Controls/IResourceNode.cs
+++ b/src/Avalonia.Base/Controls/IResourceNode.cs
@ -1,6 +1,5 @@
 using System;
-
-#nullable enable
+using Avalonia.Metadata;

 namespace Avalonia.Controls
 {
@ -12,6 +11,7 @@ namespace Avalonia.Controls
    /// (<see cref="IResourceHost"/>) and resource providers such as <see cref="ResourceDictionary"/>
    /// (see <see cref="IResourceProvider"/>).
    /// </remarks>
+    [NotClientImplementable]
    public interface IResourceNode
    {
        /// <summary>
--- a/src/Avalonia.Base/Controls/ISetInheritanceParent.cs
+++ b/src/Avalonia.Base/Controls/ISetInheritanceParent.cs
@ -1,4 +1,4 @@
-#nullable enable
+using Avalonia.Metadata;

 namespace Avalonia.Controls
 {
@ -10,6 +10,7 @@ namespace Avalonia.Controls
    /// Additionally, <see cref="ISetLogicalParent"/> also sets the inheritance parent; this
    /// interface is only needed where the logical and inheritance parents differ.
    /// </remarks>
+    [NotClientImplementable]
    public interface ISetInheritanceParent
    {
        /// <summary>
--- a/src/Avalonia.Base/Controls/ISetLogicalParent.cs
+++ b/src/Avalonia.Base/Controls/ISetLogicalParent.cs
@ -1,6 +1,5 @@
 using Avalonia.LogicalTree;
-
-#nullable enable
+using Avalonia.Metadata;

 namespace Avalonia.Controls
 {
@ -10,6 +9,7 @@ namespace Avalonia.Controls
    /// <remarks>
    /// You should not usually need to use this interface - it is for advanced scenarios only.
    /// </remarks>
+    [NotClientImplementable]
    public interface ISetLogicalParent
    {
        /// <summary>
--- a/src/Avalonia.Base/Data/Core/IPropertyInfo.cs
+++ b/src/Avalonia.Base/Data/Core/IPropertyInfo.cs
@ -1,7 +1,9 @@
 using System;
+using Avalonia.Metadata;

 namespace Avalonia.Data.Core
 {
+    [NotClientImplementable]
    public interface IPropertyInfo
    {
        string Name { get; }
--- a/src/Avalonia.Base/Data/Core/Plugins/InpcPropertyAccessorPlugin.cs
+++ b/src/Avalonia.Base/Data/Core/Plugins/InpcPropertyAccessorPlugin.cs
@ -17,7 +17,7 @@ namespace Avalonia.Data.Core.Plugins
            new Dictionary<(Type, string), PropertyInfo?>();

        /// <inheritdoc/>
-        public bool Match(object obj, string propertyName) => GetFirstPropertyWithName(obj.GetType(), propertyName) != null;
+        public bool Match(object obj, string propertyName) => GetFirstPropertyWithName(obj, propertyName) != null;

        /// <summary>
        /// Starts monitoring the value of a property on an object.
@ -36,7 +36,7 @@ namespace Avalonia.Data.Core.Plugins
            if (!reference.TryGetTarget(out var instance) || instance is null)
                return null;

-            var p = GetFirstPropertyWithName(instance.GetType(), propertyName);
+            var p = GetFirstPropertyWithName(instance, propertyName);

            if (p != null)
            {
@ -50,8 +50,16 @@ namespace Avalonia.Data.Core.Plugins
            }
        }

-        private PropertyInfo? GetFirstPropertyWithName(Type type, string propertyName)
+        private const BindingFlags PropertyBindingFlags =
+            BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static | BindingFlags.Instance;
+        
+        private PropertyInfo? GetFirstPropertyWithName(object instance, string propertyName)
        {
+            if (instance is IReflectableType reflectableType)
+                return reflectableType.GetTypeInfo().GetProperty(propertyName, PropertyBindingFlags);
+
+            var type = instance.GetType();
+            
            var key = (type, propertyName);

            if (!_propertyLookup.TryGetValue(key, out var propertyInfo))
@ -66,10 +74,7 @@ namespace Avalonia.Data.Core.Plugins
        {
            PropertyInfo? found = null;

-            const BindingFlags bindingFlags =
-                BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static | BindingFlags.Instance;
-
-            var properties = type.GetProperties(bindingFlags);
+            var properties = type.GetProperties(PropertyBindingFlags);

            foreach (PropertyInfo propertyInfo in properties)
            {
--- a/src/Avalonia.Base/Data/IBinding.cs
+++ b/src/Avalonia.Base/Data/IBinding.cs
@ -1,8 +1,11 @@
+using Avalonia.Metadata;
+
 namespace Avalonia.Data
 {
    /// <summary>
    /// Holds a binding that can be applied to a property on an object.
    /// </summary>
+    [NotClientImplementable]
    public interface IBinding
    {
        /// <summary>
--- a/src/Avalonia.Base/DirectPropertyBase.cs
+++ b/src/Avalonia.Base/DirectPropertyBase.cs
@ -2,7 +2,6 @@
 using Avalonia.Data;
 using Avalonia.Reactive;
 using Avalonia.Styling;
-using Avalonia.Utilities;

 namespace Avalonia
 {
@ -188,10 +187,10 @@ namespace Avalonia
            }
            else if (value is ITemplate template && !typeof(ITemplate).IsAssignableFrom(PropertyType))
            {
-                return new PropertySetterLazyInstance<TValue>(
+                return new PropertySetterTemplateInstance<TValue>(
                    target,
                    this,
-                    () => (TValue)template.Build());
+                    template);
            }
            else
            {
--- a/src/Avalonia.Base/IAvaloniaObject.cs
+++ b/src/Avalonia.Base/IAvaloniaObject.cs
@ -1,11 +1,13 @@
 using System;
 using Avalonia.Data;
+using Avalonia.Metadata;

 namespace Avalonia
 {
    /// <summary>
    /// Interface for getting/setting <see cref="AvaloniaProperty"/> values on an object.
    /// </summary>
+    [NotClientImplementable]
    public interface IAvaloniaObject
    {
        /// <summary>
--- a/src/Avalonia.Base/IDataContextProvider.cs
+++ b/src/Avalonia.Base/IDataContextProvider.cs
@ -1,10 +1,11 @@
-#nullable enable
+using Avalonia.Metadata;

 namespace Avalonia
 {
    /// <summary>
    /// Defines an element with a data context that can be used for binding.
    /// </summary>
+    [NotClientImplementable]
    public interface IDataContextProvider : IAvaloniaObject
    {
        /// <summary>
--- a/src/Avalonia.Base/IDirectPropertyAccessor.cs
+++ b/src/Avalonia.Base/IDirectPropertyAccessor.cs
@ -1,4 +1,5 @@
 using System;
+using Avalonia.Metadata;

 namespace Avalonia
 {
--- a/src/Avalonia.Base/IDirectPropertyMetadata.cs
+++ b/src/Avalonia.Base/IDirectPropertyMetadata.cs
@ -1,8 +1,11 @@
+using Avalonia.Metadata;
+
 namespace Avalonia
 {
    /// <summary>
    /// Untyped interface to <see cref="DirectPropertyMetadata{TValue}"/>
    /// </summary>
+    [NotClientImplementable]
    public interface IDirectPropertyMetadata
    {
        /// <summary>
--- a/src/Avalonia.Base/IStyledElement.cs
+++ b/src/Avalonia.Base/IStyledElement.cs
@ -2,12 +2,12 @@
 using System.ComponentModel;
 using Avalonia.Controls;
 using Avalonia.LogicalTree;
+using Avalonia.Metadata;
 using Avalonia.Styling;

-#nullable enable
-
 namespace Avalonia
 {
+    [NotClientImplementable]
    public interface IStyledElement :
        IStyleable,
        IStyleHost,
--- a/src/Avalonia.Base/IStyledPropertyMetadata.cs
+++ b/src/Avalonia.Base/IStyledPropertyMetadata.cs
@ -1,8 +1,11 @@
+using Avalonia.Metadata;
+
 namespace Avalonia
 {
    /// <summary>
    /// Untyped interface to <see cref="StyledPropertyMetadata{TValue}"/>
    /// </summary>
+    [NotClientImplementable]
    public interface IStyledPropertyMetadata
    {
        /// <summary>
--- a/src/Avalonia.Base/Input/IAccessKeyHandler.cs
+++ b/src/Avalonia.Base/Input/IAccessKeyHandler.cs
@ -1,8 +1,11 @@
+using Avalonia.Metadata;
+
 namespace Avalonia.Input
 {
    /// <summary>
    /// Defines the interface for classes that handle access keys for a window.
    /// </summary>
+    [Unstable]
    public interface IAccessKeyHandler
    {
        /// <summary>
--- a/src/Avalonia.Base/Input/IFocusManager.cs
+++ b/src/Avalonia.Base/Input/IFocusManager.cs
@ -1,8 +1,11 @@
+using Avalonia.Metadata;
+
 namespace Avalonia.Input
 {
    /// <summary>
    /// Manages focus for the application.
    /// </summary>
+    [NotClientImplementable]
    public interface IFocusManager
    {
        /// <summary>
--- a/src/Avalonia.Base/Input/IInputDevice.cs
+++ b/src/Avalonia.Base/Input/IInputDevice.cs
@ -1,7 +1,9 @@
 using Avalonia.Input.Raw;
+using Avalonia.Metadata;

 namespace Avalonia.Input
 {
+    [NotClientImplementable]
    public interface IInputDevice
    {
        /// <summary>
--- a/src/Avalonia.Base/Input/IInputElement.cs
+++ b/src/Avalonia.Base/Input/IInputElement.cs
@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using Avalonia.Interactivity;
+using Avalonia.Metadata;
 using Avalonia.VisualTree;

 #nullable enable
@ -10,6 +11,7 @@ namespace Avalonia.Input
    /// <summary>
    /// Defines input-related functionality for a control.
    /// </summary>
+    [NotClientImplementable]
    public interface IInputElement : IInteractive, IVisual
    {
        /// <summary>
--- a/src/Avalonia.Base/Input/IInputManager.cs
+++ b/src/Avalonia.Base/Input/IInputManager.cs
@ -1,5 +1,6 @@
 using System;
 using Avalonia.Input.Raw;
+using Avalonia.Metadata;

 namespace Avalonia.Input
 {
@ -7,6 +8,7 @@ namespace Avalonia.Input
    /// Receives input from the windowing subsystem and dispatches it to interested parties
    /// for processing.
    /// </summary>
+    [NotClientImplementable]
    public interface IInputManager
    {
        /// <summary>
--- a/src/Avalonia.Base/Input/IInputRoot.cs
+++ b/src/Avalonia.Base/Input/IInputRoot.cs
@ -1,8 +1,11 @@
+using Avalonia.Metadata;
+
 namespace Avalonia.Input
 {
    /// <summary>
    /// Defines the interface for top-level input elements.
    /// </summary>
+    [NotClientImplementable]
    public interface IInputRoot : IInputElement
    {
        /// <summary>
--- a/src/Avalonia.Base/Input/IKeyboardDevice.cs
+++ b/src/Avalonia.Base/Input/IKeyboardDevice.cs
@ -1,5 +1,6 @@
 using System;
 using System.ComponentModel;
+using Avalonia.Metadata;

 namespace Avalonia.Input
 {
@ -50,6 +51,7 @@ namespace Avalonia.Input
        KeyboardMask = Alt | Control | Shift | Meta
    }

+    [NotClientImplementable]
    public interface IKeyboardDevice : IInputDevice, INotifyPropertyChanged
    {
        IInputElement? FocusedElement { get; }
--- a/src/Avalonia.Base/Input/IKeyboardNavigationHandler.cs
+++ b/src/Avalonia.Base/Input/IKeyboardNavigationHandler.cs
@ -1,8 +1,11 @@
+using Avalonia.Metadata;
+
 namespace Avalonia.Input
 {
    /// <summary>
    /// Defines the interface for classes that handle keyboard navigation for a window.
    /// </summary>
+    [Unstable]
    public interface IKeyboardNavigationHandler
    {
        /// <summary>
--- a/src/Avalonia.Base/Input/IMainMenu.cs
+++ b/src/Avalonia.Base/Input/IMainMenu.cs
@ -1,5 +1,6 @@
 using System;
 using Avalonia.Interactivity;
+using Avalonia.Metadata;
 using Avalonia.VisualTree;

 namespace Avalonia.Input
@ -7,6 +8,7 @@ namespace Avalonia.Input
    /// <summary>
    /// Defines the interface for a window's main menu.
    /// </summary>
+    [NotClientImplementable]
    public interface IMainMenu : IVisual
    {
        /// <summary>
--- a/src/Avalonia.Base/Input/IMouseDevice.cs
+++ b/src/Avalonia.Base/Input/IMouseDevice.cs
@ -1,10 +1,12 @@
 using System;
+using Avalonia.Metadata;

 namespace Avalonia.Input
 {
    /// <summary>
    /// Represents a mouse device.
    /// </summary>
+    [NotClientImplementable]
    public interface IMouseDevice : IPointerDevice
    {
        /// <summary>
--- a/src/Avalonia.Base/Input/IPointer.cs
+++ b/src/Avalonia.Base/Input/IPointer.cs
@ -1,5 +1,8 @@
+using Avalonia.Metadata;
+
 namespace Avalonia.Input
 {
+    [NotClientImplementable]
    public interface IPointer
    {
        int Id { get; }
--- a/src/Avalonia.Base/Input/IPointerDevice.cs
+++ b/src/Avalonia.Base/Input/IPointerDevice.cs
@ -1,9 +1,11 @@
 using System;
 using Avalonia.VisualTree;
 using Avalonia.Input.Raw;
+using Avalonia.Metadata;

 namespace Avalonia.Input
 {
+    [NotClientImplementable]
    public interface IPointerDevice : IInputDevice
    {
        /// <inheritdoc cref="IPointer.Captured" />
--- a/src/Avalonia.Base/Input/InputElement.cs
+++ b/src/Avalonia.Base/Input/InputElement.cs
@ -94,7 +94,7 @@ namespace Avalonia.Input
        /// </summary>
        public static readonly RoutedEvent<KeyEventArgs> KeyDownEvent =
            RoutedEvent.Register<InputElement, KeyEventArgs>(
-                "KeyDown",
+                nameof(KeyDown),
                RoutingStrategies.Tunnel | RoutingStrategies.Bubble);

        /// <summary>
@ -102,7 +102,7 @@ namespace Avalonia.Input
        /// </summary>
        public static readonly RoutedEvent<KeyEventArgs> KeyUpEvent =
            RoutedEvent.Register<InputElement, KeyEventArgs>(
-                "KeyUp",
+                nameof(KeyUp),
                RoutingStrategies.Tunnel | RoutingStrategies.Bubble);

        /// <summary>
@ -116,7 +116,7 @@ namespace Avalonia.Input
        /// </summary>
        public static readonly RoutedEvent<TextInputEventArgs> TextInputEvent =
            RoutedEvent.Register<InputElement, TextInputEventArgs>(
-                "TextInput",
+                nameof(TextInput),
                RoutingStrategies.Tunnel | RoutingStrategies.Bubble);
        
        /// <summary>
@ -124,7 +124,7 @@ namespace Avalonia.Input
        /// </summary>
        public static readonly RoutedEvent<TextInputMethodClientRequestedEventArgs> TextInputMethodClientRequestedEvent =
            RoutedEvent.Register<InputElement, TextInputMethodClientRequestedEventArgs>(
-                "TextInputMethodClientRequested",
+                nameof(TextInputMethodClientRequested),
                RoutingStrategies.Tunnel | RoutingStrategies.Bubble);

        /// <summary>
@ -144,7 +144,7 @@ namespace Avalonia.Input
        /// </summary>
        public static readonly RoutedEvent<PointerEventArgs> PointerMovedEvent =
            RoutedEvent.Register<InputElement, PointerEventArgs>(
-                "PointerMove",
+                nameof(PointerMoved),
                RoutingStrategies.Tunnel | RoutingStrategies.Bubble);

        /// <summary>
@ -152,7 +152,7 @@ namespace Avalonia.Input
        /// </summary>
        public static readonly RoutedEvent<PointerPressedEventArgs> PointerPressedEvent =
            RoutedEvent.Register<InputElement, PointerPressedEventArgs>(
-                "PointerPressed",
+                nameof(PointerPressed),
                RoutingStrategies.Tunnel | RoutingStrategies.Bubble);

        /// <summary>
@ -160,7 +160,7 @@ namespace Avalonia.Input
        /// </summary>
        public static readonly RoutedEvent<PointerReleasedEventArgs> PointerReleasedEvent =
            RoutedEvent.Register<InputElement, PointerReleasedEventArgs>(
-                "PointerReleased",
+                nameof(PointerReleased),
                RoutingStrategies.Tunnel | RoutingStrategies.Bubble);
        
        /// <summary>
@ -168,7 +168,7 @@ namespace Avalonia.Input
        /// </summary>
        public static readonly RoutedEvent<PointerCaptureLostEventArgs> PointerCaptureLostEvent =
            RoutedEvent.Register<InputElement, PointerCaptureLostEventArgs>(
-                "PointerCaptureLost", 
+                nameof(PointerCaptureLost), 
                RoutingStrategies.Direct);

        /// <summary>
@ -176,7 +176,7 @@ namespace Avalonia.Input
        /// </summary>
        public static readonly RoutedEvent<PointerWheelEventArgs> PointerWheelChangedEvent =
            RoutedEvent.Register<InputElement, PointerWheelEventArgs>(
-                "PointerWheelChanged",
+                nameof(PointerWheelChanged),
                RoutingStrategies.Tunnel | RoutingStrategies.Bubble);

        /// <summary>
--- a/src/Avalonia.Base/Input/Platform/IClipboard.cs
+++ b/src/Avalonia.Base/Input/Platform/IClipboard.cs
@ -1,7 +1,9 @@
 using System.Threading.Tasks;
+using Avalonia.Metadata;

 namespace Avalonia.Input.Platform
 {
+    [NotClientImplementable]
    public interface IClipboard
    {
        Task<string> GetTextAsync();
--- a/src/Avalonia.Base/Input/Platform/IPlatformDragSource.cs
+++ b/src/Avalonia.Base/Input/Platform/IPlatformDragSource.cs
@ -1,7 +1,9 @@
 using System.Threading.Tasks;
+using Avalonia.Metadata;

 namespace Avalonia.Input.Platform
 {
+    [Unstable]
    public interface IPlatformDragSource
    {
        Task<DragDropEffects> DoDragDrop(PointerEventArgs triggerEvent, IDataObject data, DragDropEffects allowedEffects);
--- a/src/Avalonia.Base/Input/Raw/IDragDropDevice.cs
+++ b/src/Avalonia.Base/Input/Raw/IDragDropDevice.cs
@ -1,5 +1,8 @@
-namespace Avalonia.Input.Raw
+using Avalonia.Metadata;
+
+namespace Avalonia.Input.Raw
 {
+    [NotClientImplementable]
    public interface IDragDropDevice : IInputDevice
    {
    }
--- a/src/Avalonia.Base/Input/TextInput/ITextInputMethodImpl.cs
+++ b/src/Avalonia.Base/Input/TextInput/ITextInputMethodImpl.cs
@ -1,5 +1,8 @@
+using Avalonia.Metadata;
+
 namespace Avalonia.Input.TextInput
 {
+    [Unstable]
    public interface ITextInputMethodImpl
    {
        void SetClient(ITextInputMethodClient? client);
@ -8,6 +11,7 @@ namespace Avalonia.Input.TextInput
        void Reset();
    }
    
+    [NotClientImplementable]
    public interface ITextInputMethodRoot : IInputRoot
    {
        ITextInputMethodImpl? InputMethod { get; }
--- a/src/Avalonia.Base/Interactivity/IInteractive.cs
+++ b/src/Avalonia.Base/Interactivity/IInteractive.cs
@ -1,4 +1,5 @@
 using System;
+using Avalonia.Metadata;

 #nullable enable

@ -7,6 +8,7 @@ namespace Avalonia.Interactivity
    /// <summary>
    /// Interface for objects that raise routed events.
    /// </summary>
+    [NotClientImplementable]
    public interface IInteractive
    {
        /// <summary>
--- a/src/Avalonia.Base/Layout/ILayoutManager.cs
+++ b/src/Avalonia.Base/Layout/ILayoutManager.cs
@ -1,12 +1,12 @@
 using System;
-
-#nullable enable
+using Avalonia.Metadata;

 namespace Avalonia.Layout
 {
    /// <summary>
    /// Manages measuring and arranging of controls.
    /// </summary>
+    [NotClientImplementable]
    public interface ILayoutManager : IDisposable
    {
        /// <summary>
--- a/src/Avalonia.Base/Layout/ILayoutRoot.cs
+++ b/src/Avalonia.Base/Layout/ILayoutRoot.cs
@ -1,8 +1,11 @@
+using Avalonia.Metadata;
+
 namespace Avalonia.Layout
 {
    /// <summary>
    /// Defines the root of a layoutable tree.
    /// </summary>
+    [NotClientImplementable]
    public interface ILayoutRoot : ILayoutable
    {
        /// <summary>
--- a/src/Avalonia.Base/Layout/ILayoutable.cs
+++ b/src/Avalonia.Base/Layout/ILayoutable.cs
@ -1,12 +1,12 @@
+using Avalonia.Metadata;
 using Avalonia.VisualTree;

-#nullable enable
-
 namespace Avalonia.Layout
 {
    /// <summary>
    /// Defines layout-related functionality for a control.
    /// </summary>
+    [NotClientImplementable]
    public interface ILayoutable : IVisual
    {
        /// <summary>
--- a/src/Avalonia.Base/Layout/Layoutable.cs
+++ b/src/Avalonia.Base/Layout/Layoutable.cs
@ -141,7 +141,6 @@ namespace Avalonia.Layout
        static Layoutable()
        {
            AffectsMeasure<Layoutable>(
-                IsVisibleProperty,
                WidthProperty,
                HeightProperty,
                MinWidthProperty,
@ -791,6 +790,25 @@ namespace Avalonia.Layout
        {
        }

+        protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
+        {
+            base.OnPropertyChanged(change);
+
+            if (change.Property == IsVisibleProperty)
+            {
+                DesiredSize = default;
+
+                // All changes to visibility cause the parent element to be notified.
+                this.GetVisualParent<ILayoutable>()?.ChildDesiredSizeChanged(this);
+
+                // We only invalidate outselves when visibility is changed to true.
+                if (change.GetNewValue<bool>())
+                {
+                    InvalidateMeasure();
+                }
+            }
+        }
+
        /// <inheritdoc/>
        protected sealed override void OnVisualParentChanged(IVisual? oldParent, IVisual? newParent)
        {
--- a/src/Avalonia.Base/Layout/UniformGridLayout.cs
+++ b/src/Avalonia.Base/Layout/UniformGridLayout.cs
@ -116,7 +116,7 @@ namespace Avalonia.Layout
        /// Defines the <see cref="MaximumRowsOrColumnsProperty"/> property.
        /// </summary>
        public static readonly StyledProperty<int> MaximumRowsOrColumnsProperty =
-            AvaloniaProperty.Register<UniformGridLayout, int>(nameof(MinItemWidth));
+            AvaloniaProperty.Register<UniformGridLayout, int>(nameof(MaximumRowsOrColumns));

        /// <summary>
        /// Defines the <see cref="Orientation"/> property.
--- a/src/Avalonia.Base/LogicalTree/ILogical.cs
+++ b/src/Avalonia.Base/LogicalTree/ILogical.cs
@ -1,12 +1,14 @@
 using System;
 using Avalonia.Collections;
 using Avalonia.Controls;
+using Avalonia.Metadata;

 namespace Avalonia.LogicalTree
 {
    /// <summary>
    /// Represents a node in the logical tree.
    /// </summary>
+    [NotClientImplementable]
    public interface ILogical
    {
        /// <summary>
--- a/src/Avalonia.Base/LogicalTree/ILogicalRoot.cs
+++ b/src/Avalonia.Base/LogicalTree/ILogicalRoot.cs
@ -1,8 +1,11 @@
-namespace Avalonia.LogicalTree
+using Avalonia.Metadata;
+
+namespace Avalonia.LogicalTree
 {
    /// <summary>
    /// Represents a root of a logical tree.
    /// </summary>
+    [NotClientImplementable]
    public interface ILogicalRoot : ILogical
    {
    }
--- a/src/Avalonia.Base/Media/ConicGradientBrush.cs
+++ b/src/Avalonia.Base/Media/ConicGradientBrush.cs
@ -11,7 +11,7 @@ namespace Avalonia.Media
        /// Defines the <see cref="Center"/> property.
        /// </summary>
        public static readonly StyledProperty<RelativePoint> CenterProperty =
-            AvaloniaProperty.Register<RadialGradientBrush, RelativePoint>(
+            AvaloniaProperty.Register<ConicGradientBrush, RelativePoint>(
                nameof(Center),
                RelativePoint.Center);

@ -19,7 +19,7 @@ namespace Avalonia.Media
        /// Defines the <see cref="Angle"/> property.
        /// </summary>
        public static readonly StyledProperty<double> AngleProperty =
-            AvaloniaProperty.Register<RadialGradientBrush, double>(
+            AvaloniaProperty.Register<ConicGradientBrush, double>(
                nameof(Angle),
                0);
        
--- a/src/Avalonia.Base/Media/IBrush.cs
+++ b/src/Avalonia.Base/Media/IBrush.cs
@ -1,4 +1,5 @@
 using System.ComponentModel;
+using Avalonia.Metadata;

 namespace Avalonia.Media
 {
@ -6,6 +7,7 @@ namespace Avalonia.Media
    /// Describes how an area is painted.
    /// </summary>
    [TypeConverter(typeof(BrushConverter))]
+    [NotClientImplementable]
    public interface IBrush
    {
        /// <summary>
--- a/src/Avalonia.Base/Media/IConicGradientBrush.cs
+++ b/src/Avalonia.Base/Media/IConicGradientBrush.cs
@ -1,8 +1,11 @@
-namespace Avalonia.Media
+using Avalonia.Metadata;
+
+namespace Avalonia.Media
 {
    /// <summary>
    /// Paints an area with a conic gradient.
    /// </summary>
+    [NotClientImplementable]
    public interface IConicGradientBrush : IGradientBrush
    {
        /// <summary>
--- a/src/Avalonia.Base/Media/IDashStyle.cs
+++ b/src/Avalonia.Base/Media/IDashStyle.cs
@ -1,10 +1,12 @@
 using System.Collections.Generic;
+using Avalonia.Metadata;

 namespace Avalonia.Media
 {
    /// <summary>
    /// Represents the sequence of dashes and gaps that will be applied by a <see cref="Pen"/>.
    /// </summary>
+    [NotClientImplementable]
    public interface IDashStyle
    {
        /// <summary>
--- a/src/Avalonia.Base/Media/IExperimentalAcrylicMaterial.cs
+++ b/src/Avalonia.Base/Media/IExperimentalAcrylicMaterial.cs
@ -1,8 +1,11 @@
-namespace Avalonia.Media
+using Avalonia.Metadata;
+
+namespace Avalonia.Media
 {
    /// <summary>
    /// Experimental Interface for producing Acrylic-like materials.
    /// </summary>
+    [NotClientImplementable]
    public interface IExperimentalAcrylicMaterial
    {
        /// <summary>
--- a/src/Avalonia.Base/Media/IGradientBrush.cs
+++ b/src/Avalonia.Base/Media/IGradientBrush.cs
@ -1,10 +1,12 @@
 using System.Collections.Generic;
+using Avalonia.Metadata;

 namespace Avalonia.Media
 {
    /// <summary>
    /// A brush that draws with a gradient.
    /// </summary>
+    [NotClientImplementable]
    public interface IGradientBrush : IBrush
    {
        /// <summary>
--- a/src/Avalonia.Base/Media/IGradientStop.cs
+++ b/src/Avalonia.Base/Media/IGradientStop.cs
@ -1,8 +1,11 @@
-namespace Avalonia.Media
+using Avalonia.Metadata;
+
+namespace Avalonia.Media
 {
    /// <summary>
    /// Describes the location and color of a transition point in a gradient.
    /// </summary>
+    [NotClientImplementable]
    public interface IGradientStop
    {
        /// <summary>
--- a/src/Avalonia.Base/Media/IImageBrush.cs
+++ b/src/Avalonia.Base/Media/IImageBrush.cs
@ -1,10 +1,12 @@
 using Avalonia.Media.Imaging;
+using Avalonia.Metadata;

 namespace Avalonia.Media
 {
    /// <summary>
    /// Paints an area with an <see cref="IBitmap"/>.
    /// </summary>
+    [NotClientImplementable]
    public interface IImageBrush : ITileBrush
    {
        /// <summary>
@ -12,4 +14,4 @@ namespace Avalonia.Media
        /// </summary>
        IBitmap Source { get; }
    }
-}
+}
--- a/src/Avalonia.Base/Media/ILinearGradientBrush.cs
+++ b/src/Avalonia.Base/Media/ILinearGradientBrush.cs
@ -1,8 +1,11 @@
-namespace Avalonia.Media
+using Avalonia.Metadata;
+
+namespace Avalonia.Media
 {
    /// <summary>
    /// A brush that draws with a linear gradient.
    /// </summary>
+    [NotClientImplementable]
    public interface ILinearGradientBrush : IGradientBrush
    {
        /// <summary>
@ -15,4 +18,4 @@
        /// </summary>
        RelativePoint EndPoint { get; }
    }
-}
+}
--- a/src/Avalonia.Base/Media/IMutableBrush.cs
+++ b/src/Avalonia.Base/Media/IMutableBrush.cs
@ -1,10 +1,12 @@
 using System;
+using Avalonia.Metadata;

 namespace Avalonia.Media
 {
    /// <summary>
    /// Represents a mutable brush which can return an immutable clone of itself.
    /// </summary>
+    [NotClientImplementable]
    public interface IMutableBrush : IBrush, IAffectsRender
    {
        /// <summary>
--- a/src/Avalonia.Base/Media/IMutableExperimentalAcrylicMaterial.cs
+++ b/src/Avalonia.Base/Media/IMutableExperimentalAcrylicMaterial.cs
@ -1,8 +1,11 @@
-namespace Avalonia.Media
+using Avalonia.Metadata;
+
+namespace Avalonia.Media
 {
    /// <summary>
    /// Represents a mutable brush which can return an immutable clone of itself.
    /// </summary>
+    [NotClientImplementable]
    public interface IMutableExperimentalAcrylicMaterial : IExperimentalAcrylicMaterial, IAffectsRender
    {
        /// <summary>
--- a/src/Avalonia.Base/Media/IMutableTransform.cs
+++ b/src/Avalonia.Base/Media/IMutableTransform.cs
@ -1,4 +1,5 @@
 using System;
+using Avalonia.Metadata;

 namespace Avalonia.Media
 {
--- a/src/Avalonia.Base/Media/IPen.cs
+++ b/src/Avalonia.Base/Media/IPen.cs
@ -1,8 +1,11 @@
-namespace Avalonia.Media
+using Avalonia.Metadata;
+
+namespace Avalonia.Media
 {
    /// <summary>
    /// Describes how a stroke is drawn.
    /// </summary>
+    [NotClientImplementable]
    public interface IPen
    {
        /// <summary>
--- a/src/Avalonia.Base/Media/IRadialGradientBrush.cs
+++ b/src/Avalonia.Base/Media/IRadialGradientBrush.cs
@ -1,8 +1,11 @@
-namespace Avalonia.Media
+using Avalonia.Metadata;
+
+namespace Avalonia.Media
 {
    /// <summary>
    /// Paints an area with a radial gradient.
    /// </summary>
+    [NotClientImplementable]
    public interface IRadialGradientBrush : IGradientBrush
    {
        /// <summary>
@ -21,4 +24,4 @@
        /// </summary>
        double Radius { get; }
    }
-}
+}
--- a/src/Avalonia.Base/Media/ISolidColorBrush.cs
+++ b/src/Avalonia.Base/Media/ISolidColorBrush.cs
@ -1,8 +1,11 @@
+using Avalonia.Metadata;
+
 namespace Avalonia.Media
 {
    /// <summary>
    /// Fills an area with a solid color.
    /// </summary>
+    [NotClientImplementable]
    public interface ISolidColorBrush : IBrush
    {
        /// <summary>
@ -10,4 +13,4 @@ namespace Avalonia.Media
        /// </summary>
        Color Color { get; }
    }
-}
+}
--- a/src/Avalonia.Base/Media/ITileBrush.cs
+++ b/src/Avalonia.Base/Media/ITileBrush.cs
@ -1,10 +1,12 @@
 using Avalonia.Media.Imaging;
+using Avalonia.Metadata;

 namespace Avalonia.Media
-{  
+{
    /// <summary>
    /// A brush which displays a repeating image.
    /// </summary>
+    [NotClientImplementable]
    public interface ITileBrush : IBrush
    {
        /// <summary>
--- a/src/Avalonia.Base/Media/IVisualBrush.cs
+++ b/src/Avalonia.Base/Media/IVisualBrush.cs
@ -1,10 +1,12 @@
-using Avalonia.VisualTree;
+using Avalonia.Metadata;
+using Avalonia.VisualTree;

 namespace Avalonia.Media
 {
    /// <summary>
    /// Paints an area with an <see cref="IVisual"/>.
    /// </summary>
+    [NotClientImplementable]
    public interface IVisualBrush : ITileBrush
    {
        /// <summary>
@ -12,4 +14,4 @@ namespace Avalonia.Media
        /// </summary>
        IVisual Visual { get; }
    }
-}
+}
--- a/src/Avalonia.Base/Media/Imaging/IBitmap.cs
+++ b/src/Avalonia.Base/Media/Imaging/IBitmap.cs
@ -1,5 +1,6 @@
 using System;
 using System.IO;
+using Avalonia.Metadata;
 using Avalonia.Platform;
 using Avalonia.Utilities;

@ -8,6 +9,7 @@ namespace Avalonia.Media.Imaging
    /// <summary>
    /// Represents a bitmap image.
    /// </summary>
+    [NotClientImplementable]
    public interface IBitmap : IImage, IDisposable
    {
        /// <summary>
--- a/src/Avalonia.Base/Media/TextFormatting/ITextSource.cs
+++ b/src/Avalonia.Base/Media/TextFormatting/ITextSource.cs
@ -1,4 +1,6 @@
-namespace Avalonia.Media.TextFormatting
+using Avalonia.Metadata;
+
+namespace Avalonia.Media.TextFormatting
 {
    /// <summary>
    /// Produces <see cref="TextRun"/> objects that are used by the <see cref="TextFormatter"/>.
--- a/src/Avalonia.Base/Metadata/NotClientImplementableAttribute.cs
+++ b/src/Avalonia.Base/Metadata/NotClientImplementableAttribute.cs
@ -0,0 +1,17 @@
+using System;
+
+namespace Avalonia.Metadata
+{
+    /// <summary>
+    /// This interface is not intended to be implemented outside of the core Avalonia framework as
+    /// its API may change without warning.
+    /// </summary>
+    /// <remarks>
+    /// This interface is stable for consumption by a client, but should not be implemented as members
+    /// may be added to its API.
+    /// </remarks>
+    [AttributeUsage(AttributeTargets.Interface)]
+    public class NotClientImplementableAttribute : Attribute
+    {
+    }
+}
--- a/src/Avalonia.Base/Metadata/UnstableAttribute.cs
+++ b/src/Avalonia.Base/Metadata/UnstableAttribute.cs
@ -0,0 +1,12 @@
+using System;
+
+namespace Avalonia.Metadata
+{
+    /// <summary>
+    /// This API is unstable and is not covered by API compatibility guarantees between minor and
+    /// patch releases.
+    /// </summary>
+    public class UnstableAttribute : Attribute
+    {
+    }
+}
--- a/src/Avalonia.Base/Platform/IAssetLoader.cs
+++ b/src/Avalonia.Base/Platform/IAssetLoader.cs
@ -2,12 +2,14 @@ using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Reflection;
+using Avalonia.Metadata;

 namespace Avalonia.Platform
 {
    /// <summary>
    /// Loads assets compiled into the application binary.
    /// </summary>
+    [Unstable]
    public interface IAssetLoader
    {
        /// <summary>
--- a/src/Avalonia.Base/Platform/IBitmapImpl.cs
+++ b/src/Avalonia.Base/Platform/IBitmapImpl.cs
@ -1,11 +1,13 @@
 using System;
 using System.IO;
+using Avalonia.Metadata;

 namespace Avalonia.Platform
 {
    /// <summary>
    /// Defines the platform-specific interface for a <see cref="Avalonia.Media.Imaging.Bitmap"/>.
    /// </summary>
+    [Unstable]
    public interface IBitmapImpl : IDisposable
    {
        /// <summary>
--- a/src/Avalonia.Base/Platform/ICursorImpl.cs
+++ b/src/Avalonia.Base/Platform/ICursorImpl.cs
@ -1,5 +1,6 @@
 using System;
 using Avalonia.Input;
+using Avalonia.Metadata;

 #nullable enable

@ -8,6 +9,7 @@ namespace Avalonia.Platform
    /// <summary>
    /// Represents a platform implementation of a <see cref="Cursor"/>.
    /// </summary>
+    [Unstable]
    public interface ICursorImpl : IDisposable
    {
    }
--- a/src/Avalonia.Base/Platform/IDrawingContextImpl.cs
+++ b/src/Avalonia.Base/Platform/IDrawingContextImpl.cs
@ -3,12 +3,14 @@ using Avalonia.Media;
 using Avalonia.Rendering.SceneGraph;
 using Avalonia.Utilities;
 using Avalonia.Media.Imaging;
+using Avalonia.Metadata;

 namespace Avalonia.Platform
 {
    /// <summary>
    /// Defines the interface through which drawing occurs.
    /// </summary>
+    [Unstable]
    public interface IDrawingContextImpl : IDisposable
    {
        /// <summary>
--- a/src/Avalonia.Base/Platform/IFontManagerImpl.cs
+++ b/src/Avalonia.Base/Platform/IFontManagerImpl.cs
@ -1,9 +1,11 @@
 using System.Collections.Generic;
 using System.Globalization;
 using Avalonia.Media;
+using Avalonia.Metadata;

 namespace Avalonia.Platform
 {
+    [Unstable]
    public interface IFontManagerImpl
    {
        /// <summary>
--- a/src/Avalonia.Base/Platform/IGeometryImpl.cs
+++ b/src/Avalonia.Base/Platform/IGeometryImpl.cs
@ -1,10 +1,12 @@
 using Avalonia.Media;
+using Avalonia.Metadata;

 namespace Avalonia.Platform
 {
    /// <summary>
    /// Defines the platform-specific interface for a <see cref="Geometry"/>.
    /// </summary>
+    [Unstable]
    public interface IGeometryImpl
    {
        /// <summary>
--- a/src/Avalonia.Base/Platform/IGlyphRunImpl.cs
+++ b/src/Avalonia.Base/Platform/IGlyphRunImpl.cs
@ -1,9 +1,11 @@
 using System;
+using Avalonia.Metadata;

 namespace Avalonia.Platform
 {
    /// <summary>
    ///     Actual implementation of a glyph run that stores platform dependent resources.
    /// </summary>
+    [Unstable]
    public interface IGlyphRunImpl : IDisposable { }
 }
--- a/src/Avalonia.Base/Platform/IGlyphTypefaceImpl.cs
+++ b/src/Avalonia.Base/Platform/IGlyphTypefaceImpl.cs
@ -1,7 +1,9 @@
 using System;
+using Avalonia.Metadata;

 namespace Avalonia.Platform
 {
+    [Unstable]
    public interface IGlyphTypefaceImpl : IDisposable
    {
        /// <summary>
--- a/src/Avalonia.Base/Platform/IMacOSTopLevelPlatformHandle.cs
+++ b/src/Avalonia.Base/Platform/IMacOSTopLevelPlatformHandle.cs
@ -1,7 +1,9 @@
 using System;
+using Avalonia.Metadata;

 namespace Avalonia.Platform
 {
+    [Unstable]
    public interface IMacOSTopLevelPlatformHandle
    {
        IntPtr NSView { get; }
--- a/src/Avalonia.Base/Platform/IPlatformRenderInterface.cs
+++ b/src/Avalonia.Base/Platform/IPlatformRenderInterface.cs
@ -3,12 +3,14 @@ using System.Collections.Generic;
 using System.IO;
 using Avalonia.Media;
 using Avalonia.Media.Imaging;
+using Avalonia.Metadata;

 namespace Avalonia.Platform
 {
    /// <summary>
    /// Defines the main platform-specific interface for the rendering subsystem.
    /// </summary>
+    [Unstable]
    public interface IPlatformRenderInterface
    {
        /// <summary>
--- a/src/Avalonia.Base/Platform/IPlatformSettings.cs
+++ b/src/Avalonia.Base/Platform/IPlatformSettings.cs
@ -1,7 +1,9 @@
 using System;
+using Avalonia.Metadata;

 namespace Avalonia.Platform
 {
+    [Unstable]
    public interface IPlatformSettings
    {
        Size DoubleClickSize { get; }