qtbot causes crash in xfwm4

[markfink]

I am using qtbot for a while now with some (<10) testcases. I noticed that I have to restart my window manager 2 out of 5 test runs. That is why I have a console open where I can restart the window manager.
I just got the following error in the console while running the tests:

(xfwm4:8437): Gdk-ERROR **: 18:46:15.395: The program 'xfwm4' received an X Window System error.
This probably reflects a bug in the program.
The error was 'XSyncBadCounter'.
  (Details: serial 5287398 error_code 134 request_code 134 (SYNC) minor_code 3)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the GDK_SYNCHRONIZE environment
   variable to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

Probably you can not do anything since you are using a framework or something. Please just let me know if this is a known issue or if I should report this upstream and where.
Thank you!

[The-Compiler]

Yeah, pretty sure this is an issue in either your code or Qt. Not much more we can say without having a minimal, reproducible example.