diff --git a/Lib/idlelib/ScriptBinding.py b/Lib/idlelib/ScriptBinding.py
--- a/Lib/idlelib/ScriptBinding.py
+++ b/Lib/idlelib/ScriptBinding.py
@@ -26,6 +26,7 @@
 from idlelib import PyShell
 
 from idlelib.configHandler import idleConf
+from idlelib import macosxSupport
 
 IDENTCHARS = string.ascii_letters + string.digits + "_"
 
@@ -53,6 +54,9 @@
         self.flist = self.editwin.flist
         self.root = self.editwin.root
 
+        if macosxSupport.runningAsOSXApp():
+            self.editwin.text_frame.bind('<<run-module-event-2>>', self._run_module_event)
+
     def check_module_event(self, event):
         filename = self.getfilename()
         if not filename:
@@ -166,6 +170,19 @@
         interp.runcode(code)
         return 'break'
 
+    if macosxSupport.runningAsOSXApp():
+        # Tk-Cocoa in MacOSX is broken until at least 
+        # Tk 8.5.9, and without this rather
+        # crude workaround IDLE would hang when a user
+        # tries to run a module using the keyboard shortcut
+        # (the menu item works fine).
+        _run_module_event = run_module_event
+
+        def run_module_event(self, event):
+            self.editwin.text_frame.after(200, 
+                lambda: self.editwin.text_frame.event_generate('<<run-module-event-2>>'))
+            return 'break'
+
     def getfilename(self):
         """Get source filename.  If not saved, offer to save (or create) file