"Search Messages" dropdown boxes are black since upgrade
Since I upgraded to Thunderbird 78, when I try to search through saved e-mails, the dropdown menus (to, for example, select "To" or "Date" for the search criterion) are black so that I cannot see what criterion I'm getting before I select it. (Once I select, the criterion does appear in black type on a white background.) Same problem for the adjacent dropdown menu (to select, for example, "doesn't contain", or "is"). I'm running Windows 10 Pro.
Wšykne wótegrona (3)
Run TB in safe mode (hold Shift when launching). Does it look different? If so, change the hardware acceleration setting in Options/General/Indexing, or reset the toolbars and controls.
I tried all of those suggestions, and still encountered the "blackout" of the dropdown menus.
Attached is a picture of my search window on TB 78.3.4/W10 with a lightweight theme; the Windows color settings are dark for the Window mode and light for the app mode. I can't say why your result is different, but I would recommend you try it in a new profile: Help/Troubleshooting, about:profiles, create a new profile, add an account, and test the display.