I toyed around a bit based on the post #11 from Alkis Georgopoulos (thank you for that, vala-panel-appmenu.sh is indeed the culprit, that was really really helpful)
One solution is change the exec line in the desktop file like: env GTK_MODULES=glade glade %f this is one solution that works. But I think a better solution would be to delete /etc/profile.d/vala- panel-appmenu.sh altogether because the environment variables GTK_MODULES and UBUNTU_MENUPROXY are both not in use in Ubuntu-MATE and AFAICT for GNOME-Desktop only. I deleted /etc/profile.d/vala-panel-appmenu.sh It works without problem and I think it is a bit more elegant. Could/should the file /etc/profile.d/vala-panel-appmenu.sh be marked as a conflict against mate-desktop-environment package ? In that case it would only be installed if the desktop is NOT Ubuntu-MATE -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1805129 Title: appmenu-gtk-module makes glade crash To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/appmenu-gtk-module/+bug/1805129/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs