chore: Adjust compatibility with non-Skia targets

src/Uno.UI.Composition/Composition/ContainerVisual.cs

@@ -2,21 +2,19 @@
 
 using System;
 
-namespace Windows.UI.Composition
+namespace Windows.UI.Composition;
+
+public partial class ContainerVisual : Visual
 {
-	public partial class ContainerVisual : Visual
-	{
-		internal ContainerVisual() : base(null!) => throw new NotSupportedException("Use the ctor with Compositor");
+	internal ContainerVisual() : base(null!) => throw new NotSupportedException("Use the ctor with Compositor");
 
-		internal ContainerVisual(Compositor compositor) : base(compositor)
-		{
-			Children = new VisualCollection(compositor, this);
-			Children.CollectionChanged += Children_CollectionChanged;
-		}
+	internal ContainerVisual(Compositor compositor) : base(compositor)
+	{
+		Children = new VisualCollection(compositor, this);
+		InitializePartial();
+	}
 
-		public VisualCollection Children { get; }
+	partial void InitializePartial();
 
-		private void Children_CollectionChanged(object? sender, EventArgs e) =>
-			IsChildrenRenderOrderDirty = true;
-	}
+	public VisualCollection Children { get; }
 }

src/Uno.UI.Composition/Composition/ContainerVisual.skia.cs

@@ -12,6 +12,11 @@ public partial class ContainerVisual : Visual
 
 	internal bool IsChildrenRenderOrderDirty { get; set; }
 
+	partial void InitializePartial()
+	{
+		Children.CollectionChanged += (s, e) => IsChildrenRenderOrderDirty = true;
+	}
+
 	internal IList<Visual> GetChildrenInRenderOrder()
 	{
 		if (IsChildrenRenderOrderDirty)