Import the MacOS toolbox modules from the Carbon package.
diff --git a/Mac/Tools/IDE/Wtraceback.py b/Mac/Tools/IDE/Wtraceback.py
index 4960ad0..51b54f3 100644
--- a/Mac/Tools/IDE/Wtraceback.py
+++ b/Mac/Tools/IDE/Wtraceback.py
@@ -3,7 +3,7 @@
 import W
 import os
 import types
-import List
+from Carbon import List
 
 
 class TraceBack: