Fix for issue5194, based on a patch by Ned Deily.
diff --git a/Lib/idlelib/Bindings.py b/Lib/idlelib/Bindings.py
index 13e2a33..74a93d3 100644
--- a/Lib/idlelib/Bindings.py
+++ b/Lib/idlelib/Bindings.py
@@ -10,6 +10,7 @@
 """
 import sys
 from idlelib.configHandler import idleConf
+from idlelib import macosxSupport
 
 menudefs = [
  # underscore prefixes character to underscore
@@ -80,7 +81,7 @@
    ]),
 ]
 
-if sys.platform == 'darwin' and '.app' in sys.executable:
+if macosxSupport.runningAsOSXApp():
     # Running as a proper MacOS application bundle. This block restructures
     # the menus a little to make them conform better to the HIG.