chore: Cleanup conflicts in host rendering

src/Uno.UI.Runtime.Skia.Gtk/GLRenderSurfaceBase.cs

@@ -61,6 +61,8 @@ public GLRenderSurfaceBase()
 			AutoRender = true;
 		}
 
+		public Widget Widget => this;
+
 		public void InvalidateRender()
 		{
 			// TODO Uno: Make this invalidation less often if possible.

src/Uno.UI.Runtime.Skia.Gtk/GtkHost.cs

@@ -240,9 +240,9 @@ private void WindowClosing(object sender, DeleteEventArgs args)
 			Gtk.Main.Quit();
 		}
 
-		private Widget BuildRenderSurfaceType()
+		private IRenderSurface BuildRenderSurfaceType()
 		{
-			if(RenderSurfaceType == null)
+			if (RenderSurfaceType == null)
 			{
 				if (OpenGLESRenderSurface.IsSupported)
 				{

src/Uno.UI.Runtime.Skia.Gtk/IRenderSurface.cs

@@ -1,7 +1,11 @@
-namespace Uno.UI.Runtime.Skia
+using Gtk;
+
+namespace Uno.UI.Runtime.Skia
 {
 	internal interface IRenderSurface
 	{
+		Widget Widget { get; }
+
 		void TakeScreenshot(string filePath);
 
 		void InvalidateRender();

src/Uno.UI.Runtime.Skia.Gtk/SoftwareRenderSurface.cs

@@ -15,6 +15,7 @@
 using Uno.UI.Runtime.Skia.Helpers.Windows;
 using Uno.UI.Runtime.Skia.Helpers.Dpi;
 using Windows.Graphics.Display;
+using Gtk;
 
 namespace Uno.UI.Runtime.Skia
 {
@@ -36,21 +37,7 @@ public SoftwareRenderSurface()
 		{
 			_displayInformation = DisplayInformation.GetForCurrentView();
 			_displayInformation.DpiChanged += OnDpiChanged;
-		}
 
-		public void InvalidateRender()
-		{
-		//TODO:MZ: Fix below conflict!
-			// TODO Uno: Make this invalidation less often if possible.
-			InvalidateOverlays();
-			Invalidate();
-			WUX.Window.InvalidateRender
-				+= () =>
-				{
-					// TODO Uno: Make this invalidation less often if possible.
-					InvalidateOverlays();
-					Invalidate();
-				};
 			_colorType = SKImageInfo.PlatformColorType;
 			// R and B channels are inverted on macOS running on arm64 CPU and this is not detected by Skia
 			if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
@@ -62,6 +49,15 @@ public void InvalidateRender()
 			}
 		}
 
+		public Widget Widget => this;
+
+		public void InvalidateRender()
+		{
+			// TODO Uno: Make this invalidation less often if possible.
+			InvalidateOverlays();
+			Invalidate();
+		}
+
 		private void OnDpiChanged(DisplayInformation sender, object args) =>
 			UpdateDpi();
 

src/Uno.UI.Runtime.Skia.Linux.FrameBuffer/FramebufferHost.cs

@@ -6,6 +6,7 @@
 using Windows.UI.Core;
 using Uno.Foundation.Extensibility;
 using System.ComponentModel;
+using Uno.UI.Xaml.Core;
 
 namespace Uno.UI.Runtime.Skia
 {
@@ -69,6 +70,27 @@ void CreateApp(ApplicationInitializationCallbackParams _)
 			_displayInformationExtension!.Renderer = _renderer;
 
 			WUX.Application.StartWithArguments(CreateApp);
+
+			WUX.Window.Current.Activated += Current_Activated;
+		}
+
+		private void Current_Activated(object sender, WindowActivatedEventArgs e)
+		{
+			var xamlRoot = CoreServices.Instance
+				.ContentRootCoordinator?
+				.CoreWindowContentRoot?
+				.XamlRoot;
+
+			if (xamlRoot is null)
+			{
+				throw new InvalidOperationException("XamlRoot was not properly initialized");
+			}
+
+			xamlRoot.InvalidateRender += _renderer!.InvalidateRender;
+
+			// Force initial render
+			_renderer.InvalidateRender();
+			WUX.Window.Current.Activated -= Current_Activated;
 		}
 	}
 }

src/Uno.UI.Runtime.Skia.Linux.FrameBuffer/Renderer.cs

@@ -22,18 +22,14 @@ public Renderer()
 			_fbDev.Init();
 
 			var resolution = _fbDev.ScreenSize;
-
-			WUX.Window.InvalidateRender
-			+= () =>
-			{
-				Invalidate();
-			};
 
 			WUX.Window.Current.OnNativeSizeChanged(new Windows.Foundation.Size(resolution.Width, resolution.Height));
 		}
 
 		public Size PixelSize => _fbDev.ScreenSize;
 
+		internal void InvalidateRender() => Invalidate();
+
 		void Invalidate()
 		{
 			int width, height;

src/Uno.UI.Runtime.Skia.Wpf/WpfHost.cs

@@ -131,8 +131,6 @@ public WpfHost(global::System.Windows.Threading.Dispatcher dispatcher, Func<WinU
 			Windows.UI.Core.CoreDispatcher.DispatchOverride = d => dispatcher.BeginInvoke(d);
 			Windows.UI.Core.CoreDispatcher.HasThreadAccessOverride = dispatcher.CheckAccess;
 
-			WinUI.Application.StartWithArguments(CreateApp);
-
 			_hostPointerHandler = new HostPointerHandler(this);			
 			WinUI.Window.Current.Activated += Current_Activated;
 

src/Uno.UI/UI/Xaml/XamlRoot.cs

@@ -3,6 +3,7 @@
 using Uno.UI.Xaml.Core;
 using Uno.UI.Xaml.Islands;
 using Windows.Foundation;
+using Windows.Graphics.Display;
 
 namespace Windows.UI.Xaml;