fix: Restore the protected virtual OnChildrenChanged in Shape

src/Uno.UI/UI/Xaml/BatchCollectionWrapper.cs

@@ -16,6 +16,12 @@ public abstract partial class BatchCollection<T> : ICollection<T>, IEnumerable<T
 	{
 		private readonly DependencyObject _owner;
 
+		/// <summary>
+		/// The owner of this collection.
+		/// This is intended to be used to redispatch to a specific instance in ** static ** CollectionChanged handlers.
+		/// </summary>
+		internal DependencyObject Owner => _owner;
+
 		public BatchCollection(DependencyObject owner)
 		{
 			_owner = owner;

src/Uno.UI/UI/Xaml/Shapes/Shape.wasm.cs

@@ -29,6 +29,7 @@ partial class Shape
 		protected Shape() : base("svg", isSvg: true)
 		{
 			SvgChildren = new UIElementCollection(this);
+			SvgChildren.CollectionChanged += OnSvgChildrenChanged;
 
 			OnStretchUpdatedPartial();
 		}
@@ -43,6 +44,18 @@ protected void InitCommonShapeProperties() // Should be called from base class c
 
 		protected abstract SvgElement GetMainSvgElement();
 
+		private static readonly NotifyCollectionChangedEventHandler OnSvgChildrenChanged = (object sender, NotifyCollectionChangedEventArgs args) =>
+		{
+			if (sender is UIElementCollection children && children.Owner is Shape shape)
+			{
+				shape.OnChildrenChanged();
+			}
+		};
+
+		protected virtual void OnChildrenChanged()
+		{
+		}
+
 		partial void OnFillUpdatedPartial()
 		{
 			UpdateHitTest();