Created attachment 295435 [details]
Backtrace to critical
Open any combo box (e.g. on this Bugzilla) in Wayland and see the following critical warning:
xdg_popup_configure: assertion 'impl->transient_for' failed
Backtrace attached. Remember that all windows must have a transient_for set in GTK+ nowadays, it's really not optional.
Is this still happening? If yes, it looks to me that fixing bug #170553
and bug #145866 would fix this as well; we may want to re-check this after
fixes for those get landed.
It's still happening with trunk from a few days ago, so if it doesn't happen with current trunk then you must have fixed it.