After changing the contents of a file in an Editor Window and closing without saving the "Save on Close" window pops up. On both MacOS and Linux the user can't do anything on the Editor Window anymore, but on Windows, not only can the user continue to write it is possible to try to close the window again. Each time the user attempts to close the editor the "Save on Close" window appears one more time.

Also, when you have 2 such windows if you say 'no' then,no matter what the answer to the second window is, IDLE crashes.

I'm not sure but this seems to me to be a Tk problem. Attached is a simple script that works completely different on different systems showing that this is probably a Tkinter or Tk bug.

I tested this on Mac with Python 2.7, 3.3, 3.4 and Tk 8.5.13. On Linux I tested with Python 3.2 and Tk 8.5.11 and on Windows with Python 3.3 and Tk 8.5.11.