I want to say that may be we can make a workaround for this issue in IDLE if it is worth. The "wont fix" resolution looks reasonable to me, but this doesn't mean that the issue couldn't be solved in principle (though the solution can be very costly). I'm closing this issue, but only because we have too  much other open IDLE issues, and with very good chance this issue will never solved.

Other issue is that it would be nice to make IDLE and Tkinter more responsive. Allow to interrupt long-running Tk operation and ask the user to save his files before quit. But this is separate issue.