diff -r 8d60c1c89105 Lib/idlelib/EditorWindow.py
--- a/Lib/idlelib/EditorWindow.py	Fri Dec 02 21:25:39 2011 +0200
+++ b/Lib/idlelib/EditorWindow.py	Mon Dec 05 01:27:18 2011 -0600
@@ -269,8 +269,7 @@
                     is_py_src = self.ispythonsource(filename)
                     self.set_indentation_params(is_py_src)
                     if is_py_src:
-                        self.color = color = self.ColorDelegator()
-                        per.insertfilter(color)
+                        self._addcolorizer()
             else:
                 io.set_filename(filename)
         self.ResetColorizer()