From cf9be70ffebe0feaa86e79cb9770e94b416122dd Mon Sep 17 00:00:00 2001
From: Dan Walmsley <dan@walms.co.uk>
Date: Wed, 28 Aug 2019 11:23:59 +0100
Subject: [PATCH] fix keeping disposed items in scene. This can cause
 application to freeze.

---
 src/Avalonia.Visuals/Rendering/DeferredRenderer.cs | 9 ++++++---
 src/Avalonia.Visuals/Rendering/SceneGraph/Scene.cs | 2 +-
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/Avalonia.Visuals/Rendering/DeferredRenderer.cs b/src/Avalonia.Visuals/Rendering/DeferredRenderer.cs
index bf1799bbdc..353445f5a6 100644
--- a/src/Avalonia.Visuals/Rendering/DeferredRenderer.cs
+++ b/src/Avalonia.Visuals/Rendering/DeferredRenderer.cs
@@ -354,9 +354,12 @@ namespace Avalonia.Rendering
 
                     foreach (var operation in node.DrawOperations)
                     {
-                        _currentDraw = operation;
-                        operation.Item.Render(context);
-                        _currentDraw = null;
+                        if (operation.Item != null)
+                        {
+                            _currentDraw = operation;
+                            operation.Item.Render(context);
+                            _currentDraw = null;
+                        }
                     }
 
                     foreach (var child in node.Children)
diff --git a/src/Avalonia.Visuals/Rendering/SceneGraph/Scene.cs b/src/Avalonia.Visuals/Rendering/SceneGraph/Scene.cs
index 1afc096c98..c31b99e2e4 100644
--- a/src/Avalonia.Visuals/Rendering/SceneGraph/Scene.cs
+++ b/src/Avalonia.Visuals/Rendering/SceneGraph/Scene.cs
@@ -150,7 +150,7 @@ namespace Avalonia.Rendering.SceneGraph
 
             index.Add(result.Visual, result);
 
-            foreach (var child in source.Children)
+            foreach (var child in source.Children.Where(x=>!x.Disposed))
             {
                 result.AddChild(Clone((VisualNode)child, result, index));
             }