Provide full arguments to __import__ so it works in packagized IDLE.
diff --git a/Tools/idle/EditorWindow.py b/Tools/idle/EditorWindow.py
index 2c19775..2ae69cf 100644
--- a/Tools/idle/EditorWindow.py
+++ b/Tools/idle/EditorWindow.py
@@ -484,7 +484,7 @@
         return extend.standard
 
     def load_extension(self, name):
-        mod = __import__(name)
+        mod = __import__(name, globals(), locals(), [])
         cls = getattr(mod, name)
         ins = cls(self)
         self.extensions[name] = ins