[f-spot] avoid crashing on the FindBar

[Stephane Delcroix <sdelcroix src gnome org>]

commit bff8d401c444efb066c932f954cfca20447a5ac2
Author: Paul Werner Bou <paul purecodes org>
Date:   Fri Nov 20 09:44:47 2009 +0100

    avoid crashing on the FindBar
    
    Fixes bgo #147872

 src/Widgets/FindBar.cs |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/Widgets/FindBar.cs b/src/Widgets/FindBar.cs
index c1b6cd3..13a4c20 100644
--- a/src/Widgets/FindBar.cs
+++ b/src/Widgets/FindBar.cs
@@ -115,7 +115,7 @@ namespace FSpot.Widgets {
 		{
 			int length = args.EndPos - args.StartPos;
 			//Log.Debug ("start {0} end {1} len {2} last {3}", args.StartPos, args.EndPos, length, last_entry_text);
-			string txt = last_entry_text.Substring (args.StartPos, length);
+			string txt = length < 0 ? last_entry_text : last_entry_text.Substring (args.StartPos, length);
 
 			for (int i = 0; i < txt.Length; i++) {
 				if (txt [i] == '(')