Created attachment 147044 [details]
Recording

SUMMARY

The comboboxes in Thunderbird's message filter configuration dialog don't close by itself and de-attach when window is moved.

STEPS TO REPRODUCE
1. Open Thunderbird 91.6.1
2. Hamburger Menu -> Tools -> Message Filters
3. Click on New
4. Set up the filter rules by clicking on one of the filter rules' comboboxes 

OBSERVED RESULT
The combobox opens, but it doesn't close if you click somewhere else, but only if you select an item or press ESC.
Also the opened list de-attaches from its control when the window is moved.

So far I could not reproduce this issue at other areas of Thunderbird, like its main menu or its main settings. 
If I interpret xeyes and xwininfo correctly, Thunderbird and all its windows don't run via XWayland, but are Wayland native.


SOFTWARE/OS VERSIONS
Operating System: openSUSE Tumbleweed 20220218
KDE Plasma Version: 5.24.1
KDE Frameworks Version: 5.90.0
Qt Version: 5.15.2
Kernel Version: 5.16.8-1-default (64-bit)
Graphics Platform: Wayland
Graphics Processor: AMD Radeon RX 580 Series