From b3ed4c86a8d8f53925babc015dcfc3e43d3608ea Mon Sep 17 00:00:00 2001
From: Daniel Grunwald <daniel@danielgrunwald.de>
Date: Sat, 10 Dec 2011 22:21:58 +0100
Subject: [PATCH] Fixed potential NullReferenceException in
 HeightTree.GetNodeByVisualPosition

---
 .../AvalonEdit/ICSharpCode.AvalonEdit/Rendering/HeightTree.cs  | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Rendering/HeightTree.cs b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Rendering/HeightTree.cs
index 77272ce29c..47b84b46f3 100644
--- a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Rendering/HeightTree.cs
+++ b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Rendering/HeightTree.cs
@@ -446,7 +446,8 @@ namespace ICSharpCode.AvalonEdit.Rendering
 					// i.e. at the end of the document, or due to rounding errors in previous loop iterations.
 					
 					// If node.lineNode isn't collapsed, return that.
-					if (node.lineNode.TotalHeight > 0)
+					// Also return node.lineNode if there is no previous node that we could return instead.
+					if (node.lineNode.TotalHeight > 0 || node.left == null)
 						return node;
 					// Otherwise, descend into left (find the last non-collapsed node)
 					node = node.left;