Altered ItemsControl to use Weak CollectionChange Subscription

src/Avalonia.Controls/ItemsControl.cs

@@ -1,6 +1,7 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
+using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Collections.Specialized;
@@ -54,6 +55,7 @@ namespace Avalonia.Controls
 
         private IEnumerable _items = new AvaloniaList<object>();
         private IItemContainerGenerator _itemContainerGenerator;
+        private IDisposable _itemsCollectionChangedSubscription;
 
         /// <summary>
         /// Initializes static members of the <see cref="ItemsControl"/> class.
@@ -326,12 +328,8 @@ namespace Avalonia.Controls
         /// <param name="e">The event args.</param>
         protected virtual void ItemsChanged(AvaloniaPropertyChangedEventArgs e)
         {
-            var incc = e.OldValue as INotifyCollectionChanged;
-
-            if (incc != null)
-            {
-                incc.CollectionChanged -= ItemsCollectionChanged;
-            }
+            _itemsCollectionChangedSubscription?.Dispose();
+            _itemsCollectionChangedSubscription = null;
 
             var oldValue = e.OldValue as IEnumerable;
             var newValue = e.NewValue as IEnumerable;
@@ -428,7 +426,7 @@ namespace Avalonia.Controls
 
             if (incc != null)
             {
-                incc.CollectionChanged += ItemsCollectionChanged;
+                _itemsCollectionChangedSubscription = incc.WeakSubscribe(ItemsCollectionChanged);
             }
         }