The patch to export the firefox/thunderbird menus to the global menu was removed in 20.04. I expect 16.04 and 18.04 are still affected though, but I haven't had a chance to look into the problem further.
The patch to export the firefox/thunderbird menus to the global menu was removed in 20.04.
I expect 16.04 and 18.04 are still affected though, but I haven't had a chance to look into the problem further.