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.
Just want to mention that:
I downloaded glade 3.38.1 as source code from glade.gnome.org and built it with
meson and ninja, as instructed, on Ubuntu 20.04 Desktop. (Had to install a lot
of packages to make it build, though).
When I run glade from bash cmd-line I get the message you are
