From c582faba1ac11e8aecaffcbbe0543bf94e72997f Mon Sep 17 00:00:00 2001
From: gumme <gumme@server.fake>
Date: Fri, 28 Mar 2014 15:36:45 +0100
Subject: [PATCH] Added null-check of ParentTree, as this have been null and
 caused exception.

---
 .../Project/OutlineView/DragTreeViewItem.cs                  | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/AddIns/DisplayBindings/WpfDesign/WpfDesign.Designer/Project/OutlineView/DragTreeViewItem.cs b/src/AddIns/DisplayBindings/WpfDesign/WpfDesign.Designer/Project/OutlineView/DragTreeViewItem.cs
index 191431c14d5..c5bd677aa0a 100644
--- a/src/AddIns/DisplayBindings/WpfDesign/WpfDesign.Designer/Project/OutlineView/DragTreeViewItem.cs
+++ b/src/AddIns/DisplayBindings/WpfDesign/WpfDesign.Designer/Project/OutlineView/DragTreeViewItem.cs
@@ -159,7 +159,10 @@ protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
 		protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e)
 		{
 			base.OnMouseLeftButtonUp(e);
-			ParentTree.ItemMouseUp(this);
+			
+			if (ParentTree != null) {
+				ParentTree.ItemMouseUp(this);
+			}
 		}
 	}
 }