diff --git a/Lib/idlelib/Bindings.py b/Lib/idlelib/Bindings.py
index a3c9fc4..1853ff9 100644
--- a/Lib/idlelib/Bindings.py
+++ b/Lib/idlelib/Bindings.py
@@ -10,6 +10,7 @@
 """
 import sys
 from configHandler import idleConf
+import macosxSupport
 
 menudefs = [
  # underscore prefixes character to underscore
@@ -80,8 +81,7 @@
    ]),
 ]
 
-import sys
-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.
 
diff --git a/Lib/idlelib/EditorWindow.py b/Lib/idlelib/EditorWindow.py
index 0b34242..5848c02 100644
--- a/Lib/idlelib/EditorWindow.py
+++ b/Lib/idlelib/EditorWindow.py
@@ -368,7 +368,7 @@
             menudict[name] = menu = Menu(mbar, name=name)
             mbar.add_cascade(label=label, menu=menu, underline=underline)
 
-        if sys.platform == 'darwin' and '.framework' in sys.executable:
+        if macosxSupport.runningAsOSXApp():
             # Insert the application menu
             menudict['application'] = menu = Menu(mbar, name='apple')
             mbar.add_cascade(label='IDLE', menu=menu)
diff --git a/Lib/idlelib/MultiCall.py b/Lib/idlelib/MultiCall.py
index 51de639..b228f57 100644
--- a/Lib/idlelib/MultiCall.py
+++ b/Lib/idlelib/MultiCall.py
@@ -33,6 +33,7 @@
 import string
 import re
 import Tkinter
+import macosxSupport
 
 # the event type constants, which define the meaning of mc_type
 MC_KEYPRESS=0; MC_KEYRELEASE=1; MC_BUTTONPRESS=2; MC_BUTTONRELEASE=3;
@@ -45,7 +46,7 @@
 MC_OPTION = 1<<6; MC_COMMAND = 1<<7
 
 # define the list of modifiers, to be used in complex event types.
-if sys.platform == "darwin" and sys.executable.count(".app"):
+if macosxSupport.runningAsOSXApp():
     _modifiers = (("Shift",), ("Control",), ("Option",), ("Command",))
     _modifier_masks = (MC_SHIFT, MC_CONTROL, MC_OPTION, MC_COMMAND)
 else:
diff --git a/Lib/idlelib/configDialog.py b/Lib/idlelib/configDialog.py
index acab053..2f66d09 100644
--- a/Lib/idlelib/configDialog.py
+++ b/Lib/idlelib/configDialog.py
@@ -19,6 +19,7 @@
 from keybindingDialog import GetKeysDialog
 from configSectionNameDialog import GetCfgSectionNameDialog
 from configHelpSourceEdit import GetHelpSourceDialog
+import macosxSupport
 
 class ConfigDialog(Toplevel):
 
@@ -69,18 +70,25 @@
                 page_names=['Fonts/Tabs','Highlighting','Keys','General'])
         frameActionButtons = Frame(self,pady=2)
         #action buttons
+        if macosxSupport.runningAsOSXApp():
+            # Changing the default padding on OSX results in unreadable
+            # text in the buttons
+            paddingArgs={}
+        else:
+            paddingArgs={'padx':6, 'pady':3}
+
         self.buttonHelp = Button(frameActionButtons,text='Help',
                 command=self.Help,takefocus=FALSE,
-                padx=6,pady=3)
+                **paddingArgs)
         self.buttonOk = Button(frameActionButtons,text='Ok',
                 command=self.Ok,takefocus=FALSE,
-                padx=6,pady=3)
+                **paddingArgs)
         self.buttonApply = Button(frameActionButtons,text='Apply',
                 command=self.Apply,takefocus=FALSE,
-                padx=6,pady=3)
+                **paddingArgs)
         self.buttonCancel = Button(frameActionButtons,text='Cancel',
                 command=self.Cancel,takefocus=FALSE,
-                padx=6,pady=3)
+                **paddingArgs)
         self.CreatePageFontTab()
         self.CreatePageHighlight()
         self.CreatePageKeys()
diff --git a/Lib/idlelib/keybindingDialog.py b/Lib/idlelib/keybindingDialog.py
index 1ce7ff4..d6d1f18 100644
--- a/Lib/idlelib/keybindingDialog.py
+++ b/Lib/idlelib/keybindingDialog.py
@@ -132,8 +132,8 @@
         order is also important: key binding equality depends on it, so
         config-keys.def must use the same ordering.
         """
-        import sys
-        if sys.platform == 'darwin' and sys.argv[0].count('.app'):
+        import macosxSupport
+        if macosxSupport.runningAsOSXApp():
             self.modifiers = ['Shift', 'Control', 'Option', 'Command']
         else:
             self.modifiers = ['Control', 'Alt', 'Shift']
diff --git a/Lib/idlelib/macosxSupport.py b/Lib/idlelib/macosxSupport.py
index 279b1cc..98b35b6 100644
--- a/Lib/idlelib/macosxSupport.py
+++ b/Lib/idlelib/macosxSupport.py
@@ -6,8 +6,12 @@
 import Tkinter
 
 def runningAsOSXApp():
-    """ Returns True iff running from the IDLE.app bundle on OSX """
-    return (sys.platform == 'darwin' and 'IDLE.app' in sys.argv[0])
+    """
+    Returns True if Python is running from within an app on OSX.
+    If so, assume that Python was built with Aqua Tcl/Tk rather than
+    X11 Tck/Tk.
+    """
+    return (sys.platform == 'darwin' and '.app' in sys.executable)
 
 def addOpenEventSupport(root, flist):
     """
diff --git a/Mac/IDLE/idlemain.py b/Mac/IDLE/idlemain.py
index 9b52738..d6803ba 100644
--- a/Mac/IDLE/idlemain.py
+++ b/Mac/IDLE/idlemain.py
@@ -3,8 +3,6 @@
 """
 import sys, os
 
-from idlelib.PyShell import main
-
 # Change the current directory the user's home directory, that way we'll get
 # a more useful default location in the open/save dialogs.
 os.chdir(os.path.expanduser('~/Documents'))
@@ -13,10 +11,54 @@
 # Make sure sys.executable points to the python interpreter inside the
 # framework, instead of at the helper executable inside the application
 # bundle (the latter works, but doesn't allow access to the window server)
-if sys.executable.endswith('-32'):
-    sys.executable = os.path.join(sys.prefix, 'bin', 'python-32')
-else:
-    sys.executable = os.path.join(sys.prefix, 'bin', 'python')
+#
+#  .../IDLE.app/
+#       Contents/
+#           MacOS/
+#               IDLE (a python script)
+#               Python{-32} (symlink)
+#           Resources/
+#               idlemain.py (this module)
+#               ...
+#
+# ../IDLE.app/Contents/MacOS/Python{-32} is symlinked to
+#       ..Library/Frameworks/Python.framework/Versions/m.n
+#                   /Resources/Python.app/Contents/MacOS/Python{-32}
+#       which is the Python interpreter executable
+#
+# The flow of control is as follows:
+# 1. IDLE.app is launched which starts python running the IDLE script
+# 2. IDLE script exports
+#       PYTHONEXECUTABLE = .../IDLE.app/Contents/MacOS/Python{-32}
+#           (the symlink to the framework python)
+# 3. IDLE script alters sys.argv and uses os.execve to replace itself with
+#       idlemain.py running under the symlinked python.
+#       This is the magic step.
+# 4. During interpreter initialization, because PYTHONEXECUTABLE is defined,
+#    sys.executable may get set to an unuseful value.
+#
+# (Note that the IDLE script and the setting of PYTHONEXECUTABLE is
+#  generated automatically by bundlebuilder in the Python 2.x build.
+#  Also, IDLE invoked via command line, i.e. bin/idle, bypasses all of
+#  this.)
+#
+# Now fix up the execution environment before importing idlelib.
+
+# Reset sys.executable to its normal value, the actual path of
+# the interpreter in the framework, by following the symlink
+# exported in PYTHONEXECUTABLE.
+pyex = os.environ['PYTHONEXECUTABLE']
+sys.executable = os.path.join(os.path.dirname(pyex), os.readlink(pyex))
+
+# Remove any sys.path entries for the Resources dir in the IDLE.app bundle.
+p = pyex.partition('.app')
+if p[2].startswith('/Contents/MacOS/Python'):
+    sys.path = [value for value in sys.path if
+            value.partition('.app') != (p[0], p[1], '/Contents/Resources')]
+
+# Unexport PYTHONEXECUTABLE so that the other Python processes started
+# by IDLE have a normal sys.executable.
+del os.environ['PYTHONEXECUTABLE']
 
 # Look for the -psn argument that the launcher adds and remove it, it will
 # only confuse the IDLE startup code.
@@ -25,6 +67,7 @@
         del sys.argv[idx]
         break
 
-#argvemulator.ArgvCollector().mainloop()
+# Now it is safe to import idlelib.
+from idlelib.PyShell import main
 if __name__ == '__main__':
     main()