From 81510372b4a8d445e083b83ac988b8fb772acfbf Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@users.noreply.github.com>
Date: Wed, 13 Feb 2019 21:01:26 +0100
Subject: [PATCH] Don't invalidate a disposed TopLevelImpl.

---
 .../Embedding/Offscreen/OffscreenTopLevelImpl.cs           | 4 +++-
 .../Remote/Server/RemoteServerTopLevelImpl.cs              | 7 +++++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/Avalonia.Controls/Embedding/Offscreen/OffscreenTopLevelImpl.cs b/src/Avalonia.Controls/Embedding/Offscreen/OffscreenTopLevelImpl.cs
index d328e1ee88..9c53dc0c10 100644
--- a/src/Avalonia.Controls/Embedding/Offscreen/OffscreenTopLevelImpl.cs
+++ b/src/Avalonia.Controls/Embedding/Offscreen/OffscreenTopLevelImpl.cs
@@ -11,11 +11,13 @@ namespace Avalonia.Controls.Embedding.Offscreen
     {
         private double _scaling = 1;
         private Size _clientSize;
+
         public IInputRoot InputRoot { get; private set; }
+        public bool IsDisposed { get; private set; }
 
         public virtual void Dispose()
         {
-            //No-op
+            IsDisposed = true;
         }
 
         public IRenderer CreateRenderer(IRenderRoot root) => new ImmediateRenderer(root);
diff --git a/src/Avalonia.Controls/Remote/Server/RemoteServerTopLevelImpl.cs b/src/Avalonia.Controls/Remote/Server/RemoteServerTopLevelImpl.cs
index 3fa0b108ec..6293cbfbfd 100644
--- a/src/Avalonia.Controls/Remote/Server/RemoteServerTopLevelImpl.cs
+++ b/src/Avalonia.Controls/Remote/Server/RemoteServerTopLevelImpl.cs
@@ -331,8 +331,11 @@ namespace Avalonia.Controls.Remote.Server
 
         public override void Invalidate(Rect rect)
         {
-            _invalidated = true;
-            Dispatcher.UIThread.Post(RenderIfNeeded);
+            if (!IsDisposed)
+            {
+                _invalidated = true;
+                Dispatcher.UIThread.Post(RenderIfNeeded);
+            }
         }
 
         public override IMouseDevice MouseDevice { get; } = new MouseDevice();