From ab60beaa54623ec65abaf73f978871f346e2027e Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Wed, 18 May 2016 00:30:20 +0100
Subject: [PATCH] Check visual parent is not already set.

When setting the visual parent of a control, make sure that it's not
already set. The code in issue #513 was trying to reparent an already
parented control, causing problems - this makes sure that this can't
happen.
---
 src/Avalonia.SceneGraph/Visual.cs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/Avalonia.SceneGraph/Visual.cs b/src/Avalonia.SceneGraph/Visual.cs
index 6ae5d80677..6ecab23d6a 100644
--- a/src/Avalonia.SceneGraph/Visual.cs
+++ b/src/Avalonia.SceneGraph/Visual.cs
@@ -442,6 +442,11 @@ namespace Avalonia
         /// <param name="value">The visual parent.</param>
         private void SetVisualParent(Visual value)
         {
+            if (value != null && _visualParent != null)
+            {
+                throw new InvalidOperationException("The control already has a visual parent.");
+            }
+
             if (_visualParent == value)
             {
                 return;