From 562e6bb3efa7feea31cd066e341315c27bf94720 Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Tue, 25 Aug 2020 13:07:47 +0200
Subject: [PATCH] Copy listeners before notifying.

As raising the event can cause the listeners to change.
---
 .../Utils/CollectionChangedEventManager.cs                | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/Avalonia.Controls/Utils/CollectionChangedEventManager.cs b/src/Avalonia.Controls/Utils/CollectionChangedEventManager.cs
index 6abba0cc8e..fa3f684747 100644
--- a/src/Avalonia.Controls/Utils/CollectionChangedEventManager.cs
+++ b/src/Avalonia.Controls/Utils/CollectionChangedEventManager.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.Specialized;
+using System.Linq;
 using System.Runtime.CompilerServices;
 using Avalonia.Threading;
 using Avalonia.Utilities;
@@ -118,16 +119,17 @@ namespace Avalonia.Controls.Utils
 
             if (sender is INotifyCollectionChanged incc && _entries.TryGetValue(incc, out var listeners))
             {
+                var l = listeners.ToList();
+
                 if (Dispatcher.UIThread.CheckAccess())
                 {
-                    Notify(incc, e, listeners);
+                    Notify(incc, e, l);
                 }
                 else
                 {
                     var inccCapture = incc;
                     var eCapture = e;
-                    var listenersCapture = listeners;
-                    Dispatcher.UIThread.Post(() => Notify(inccCapture, eCapture, listenersCapture));
+                    Dispatcher.UIThread.Post(() => Notify(inccCapture, eCapture, l));
                 }
             }
         }