Messages like this are an occasional nuisance when shutting down a tkinter app started in a terminal/console window.  I have gone to a lot of effort to suppress than in IDLE GUI tests so that other developers do not suffer the noise or puzzlement of thinking that there maybe was a test failure.

I can get them now *occasionally* if I start IDLE from a Windows console, open multiple windows, and close by right clicking the toolbar icon and selecting "Close all Windows" instead of closing properly by closing each window or selecting File => Exit.  I consider trying to fix this shutdown buglet to be low priority.  

When starting IDLE from an IDLE icon, any such messages go to /dev/NULL. 

After experimenting, I believe Baozhen started IDLE from Terminal with 'python3 -m idlelib'.  The top menu then has second entry "Python" instead of "IDLE" with first item "About Python" instead of "About IDLE".  But it brings up the "About IDLE" tk dialog box.  I also suspect  there was some shutdown action, so we must know every user action needed to reproduce the issue, and then see if it occurs in 3.8 or later. 

Ned, when I run 3.9 test.pythoninfo, I am asked to install gcc tools and maybe xcode.  Is this expected?