Description of problem: On https://github.com/stransky/gecko-dev.git package: View -> Toolbars -> missing menu
On Wayland Gtk complains that we create popup as a child of non-topmost window. It's because Firefox creates all popups as a child of main window does not honor the popup hierarchy. As a workaround we create popups as subsurface GdkWindow type and not xdg_shell popups on Wayland.
Fixed by https://github.com/stransky/gecko-dev/commit/3375f001733c4dc662c7e0f4e01da8c9ffea89de
We can't use this workaround, see: https://bugzilla.mozilla.org/show_bug.cgi?id=1423598