I'm running a python.org Mac build on Apple silicon.

Python 3.10.0a5 (v3.10.0a5:b0478d738a, Feb  2 2021, 16:30:44) 
[Clang 12.0.0 (clang-1200.0.32.29)] on darwin

Periodically, Python freezes and requires a force quit.  I'm not certain but think the trigger event is the display of a pop-up box showing attribute completions.  The box is correctly shaped but filled with a solid light gray.

I suspect the problem is partly in the O/S because after the freeze, I see something similar when clicking the system  icon, so the effect extends beyond Python.  However, the problem does not occur on my Mac with Intel silicon and it does not happen with Python 3.9 running on Apple silicon.  

This has been occurring for a while and has persisted through O/S updates.  Today, it happened on Big Sur 11.2.2.   

Will try to get a screen shot and more details when this happens again.

The event occurs often enough to make IDLE unusable for classroom demonstrations or for development.

Completions are in a Listbox.  listboxes are used for completions, stackviewer, and a few places in the settings dialog, in particular the keys list.  And maybe the drop down list for themes and keysets.  The latter two are the only one normally gray.  Try the different settings tabs.

What version of Python (and Tcl/Tk) are you running on your Intel Macn that does not fail? Currently, we use Tcl/Tk 8.6.11 with the macOS 64-bit universal2 installer variant as of Python 3.9.2 and 3.10.0a4; previously, they used 8.6.10. All other current installer variants use 8.6.8.

This time I got a screen shot showing the gray completion box that appeared just as IDLE stopped responding and froze:

https://www.dropbox.com/s/eu3wd13vytz6tt8/Screen%20Shot%202021-03-22%20at%209.37.56%20PM.png?dl=0

Am now running Python 3.10.0a6 on Big Sur 11.2.3 running on a 2020 M-1 MacBook Air.