child window collection

Author: pr8x

src/Avalonia.Controls/Window.cs

@@ -255,6 +255,11 @@ public Window(IWindowImpl impl)
         /// </summary>
         public new IWindowImpl? PlatformImpl => (IWindowImpl?)base.PlatformImpl;
 
+        /// <summary>
+        /// Gets a collection of child windows owned by this window.
+        /// </summary>
+        public IReadOnlyList<Window> ChildWindows => _children.Select(x => x.child).ToList();
+
         /// <summary>
         /// Gets or sets a value indicating how the window will size itself to fit its content.
         /// </summary>