This is an issue that mostly affects third party or user installed programs,
but would still be nice to get fixed.

A Python GTK program generally does:

> import gi
> gi.require_version('Gtk', '3.0')
> from gi.repository import Gtk

Error management should be around gi.require_version() to handle if GTK is
missing.

On all other distributions this works, but not on SUSE. The reason being that
some critical components have been packaged in python3-gobject-Gdk. This causes
the above code to succeed. But things will crash on random places later,
whenever the code hits something that is missing.

This is similar to bug 1179584, but doesn't have a similar obvious fix. 

Ideally, GTK's typelib should have a requirement on python3-gobject-Gdk if
python3-gobject is installed. I think this is possible on newer RPM, but I
don't know if openSUSE LEAP 15 has a sufficiently new RPM.

Packages designed specifically for SUSE can solve this by explicitly depending
on python3-gobject-Gdk. But things installed in other ways can't rely on that.