diff -r b6e93549de2e -r 2ba9d7e3be72 graphics/GraphicCommons.py
--- a/graphics/GraphicCommons.py	Tue Feb 26 01:14:20 2013 +0100
+++ b/graphics/GraphicCommons.py	Tue Feb 26 01:16:28 2013 +0100
@@ -381,7 +381,8 @@
         self.DataConsumers = {}
     
     def ShouldRefresh(self):
-        wx.CallAfter(self._ShouldRefresh)
+        if self:
+            wx.CallAfter(self._ShouldRefresh)
         
     def _ShouldRefresh(self):
         if DEBUG_REFRESH_LOCK.acquire(False):