diff -r 2bbe7dc920de Lib/idlelib/idle.pyw
--- a/Lib/idlelib/idle.pyw	Sat Dec 10 17:55:31 2011 -0500
+++ b/Lib/idlelib/idle.pyw	Sun Dec 11 13:25:00 2011 -0600
@@ -1,3 +1,123 @@
+
+
+from tkinter import *
+class ErrorNotify:
+    """ A class to display stderr messages when using pythonw.exe.
+        Otherwise, IDLE will abruptly terminate with no message if an
+        error occurs.
+    """
+
+    root = Tk(className="Idle")
+    root.withdraw()
+
+    def __init__(self, devnull=False):
+        self.buffer = []
+        self.afterid = None
+        self.devnull = devnull  # for stdout buffer
+
+    def __getattr__(self, *args, **kwargs):
+        return lambda *args, **kwargs: None
+
+
+    def _devnull(func):
+        def f(self, *args, **kwargs):
+            if not self.devnull:
+                return func(self, *args, **kwargs)
+            else:
+                return None
+        return f
+
+    @_devnull
+    def write(self, txt):
+        self.buffer.append(txt)
+
+        # auto flush the error buffer 100 ms after last write
+        if self.afterid is not None:
+            self.root.after_cancel(self.afterid)
+        self.afterid = self.root.after(100, self.flush)
+
+    @_devnull
+    def flush(self, *args, **kwargs):
+        if self.afterid is not None:
+            self.root.after_cancel(self.afterid)
+        try:
+            self._display()
+        except Exception as err:
+            pass # avoid recursive errors - this will only cause problems
+
+    def _display(self):
+        msg = ''.join(self.buffer)
+        self.buffer = []
+        if msg:
+            msg += '\n\n**This error may or may not be fatal. '
+            msg += 'To be safe, you should save your work.**'
+            p = self.root
+            e = self.ErrorViewer(p, 'IDLE Internal Error', msg)
+            #e.wait_window()   # uncomment to catch IDLE exiting errors
+                
+    class ErrorViewer(Toplevel): # based on TextViewer from textView.py
+        def __init__(self, master, title, text):
+            Toplevel.__init__(self, master=master)
+            self.withdraw()
+            self.configure(borderwidth=5)
+            self.bg = '#ffffff'
+            self.fg = '#000000'
+            self.CreateWidgets()
+            self.title(title)
+            self.protocol("WM_DELETE_WINDOW", self.Ok)
+            self.textView.focus_set()
+            #key bindings for this dialog
+            self.bind('<Return>',self.Ok) #dismiss dialog
+            self.textView.insert(0.0, text)
+            self.textView.config(state=DISABLED)
+            def ontop(self=self):
+                self.withdraw()
+                self.deiconify()
+                self.focus_set()
+                self.lift()
+            self.after(100, ontop)
+
+        def CreateWidgets(self):
+            frameText = Frame(self, relief=SUNKEN, height=700)
+            frameButtons = Frame(self)
+            self.buttonOk = Button(frameButtons, text='Ok',
+                                   command=self.Ok, takefocus=FALSE)
+            self.scrollbarView = Scrollbar(frameText, orient=VERTICAL,
+                                           takefocus=FALSE, highlightthickness=0)
+            self.textView = Text(frameText, wrap=WORD, highlightthickness=0,
+                                 fg=self.fg, bg=self.bg)
+            self.scrollbarView.config(command=self.textView.yview)
+            self.textView.config(yscrollcommand=self.scrollbarView.set)
+            self.buttonOk.pack()
+            self.scrollbarView.pack(side=RIGHT,fill=Y)
+            self.textView.pack(side=LEFT,expand=TRUE,fill=BOTH)
+            frameButtons.pack(side=BOTTOM,fill=X)
+            frameText.pack(side=TOP,expand=TRUE,fill=BOTH)
+
+        def Ok(self, event=None):
+            self.destroy()
+
+
+import sys
+
+##if 0: # For testing
+##    sys.__stderr__ = None
+##    sys.stderr = None
+
+if sys.__stderr__ is None:
+    sys.__stderr__ = ErrorNotify()
+    
+if sys.stderr is None:
+    sys.stderr = ErrorNotify()
+    
+if sys.__stdout__ is None:
+    sys.__stdout__ = ErrorNotify(devnull=True)
+    
+if sys.stdout is None:
+    sys.stdout = ErrorNotify(devnull=True)
+
+
+
 try:
     import idlelib.PyShell
 except ImportError: