After upgrading from F38 to F39, Thunderbird developed a black screen on first use after startup. Thunderbird works well in F38, but not in F39. Its not fatal, as invoking Thunderbird after that works properly, but the first time after every machine reboot, it fails. There are no updates that resolve this bug. I've tried it on multiple machines with different timings, but the problem is in the code.
I also ran it with the JS debug option, but it never gets that far on first run. It just locks up the same way as the main screen and the debugger also blackscreens. So it seems like something in the startup code is left waiting for a paint event or something.
The Thunderbird web site seems to be very indifferent to bugs, and there is no obvious means of submitting a bug report. Since it works well on multiple other platforms (I interchangeably use Windows, Manjaro and Ubuntu), this is probably a Fedora-specific bug and not a Thunderbird bug.
This feels like a Gnome timing bug causing a missed event issue. How do you look at the event (and a missed event) messages in Gnome to debug this? Assuming that I can pinpoint a failing Gnome event, where do I submit this bug?