From cc58ce44b6be1ee0dd9244b61f9d84de171c235e Mon Sep 17 00:00:00 2001
From: Alexandr <975396+masterdidoo@users.noreply.github.com>
Date: Thu, 26 Jul 2018 12:16:39 +0400
Subject: [PATCH] fix NullReferenceException in LayoutAnchorableTabItem

---
 .../Xceed.Wpf.AvalonDock/Controls/LayoutAnchorableTabItem.cs   | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/ExtendedWPFToolkitSolution/Src/Xceed.Wpf.AvalonDock/Controls/LayoutAnchorableTabItem.cs b/ExtendedWPFToolkitSolution/Src/Xceed.Wpf.AvalonDock/Controls/LayoutAnchorableTabItem.cs
index 743e0265..9d34c11f 100644
--- a/ExtendedWPFToolkitSolution/Src/Xceed.Wpf.AvalonDock/Controls/LayoutAnchorableTabItem.cs
+++ b/ExtendedWPFToolkitSolution/Src/Xceed.Wpf.AvalonDock/Controls/LayoutAnchorableTabItem.cs
@@ -181,7 +181,8 @@ namespace Xceed.Wpf.AvalonDock.Controls
     {
       base.OnMouseEnter( e );
 
-      if( _draggingItem != this &&
+      if( _draggingItem != null && 
+          _draggingItem != this &&
           e.LeftButton == MouseButtonState.Pressed )
       {
         var model = Model;