[gimp] Do not access transform tool handles if NULL or stales

[Massimo Valentini <mvalentini src gnome org>]

commit 27feccc4a4e405795fc9e3555226562b652d01b4
Author: Massimo Valentini <mvalentini src gnome org>
Date:   Tue Sep 13 18:03:30 2011 +0200

    Do not access transform tool handles if NULL or stales
    
    For example starting GIMP and pressing
    
    Ctrl-N Enter Shift-T (or Shift-R or Shift-P)
    
    showed warnings on the console, and with window manager's
    focus mode set to 'click' it was also possible to crash GIMP.

 app/tools/gimptransformtool.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/app/tools/gimptransformtool.c b/app/tools/gimptransformtool.c
index 21cbf3f..007d0f6 100644
--- a/app/tools/gimptransformtool.c
+++ b/app/tools/gimptransformtool.c
@@ -473,7 +473,7 @@ gimp_transform_tool_oper_update (GimpTool         *tool,
   GimpDrawTool      *draw_tool = GIMP_DRAW_TOOL (tool);
   TransformAction    function  = TRANSFORM_HANDLE_NONE;
 
-  if (display != tool->display)
+  if (display != tool->display || draw_tool->item == NULL)
     {
       gimp_transform_tool_set_function (tr_tool, function);
       return;