Please port to PyGObject for GTK3 for python3

[vt-alt]

See https://pygobject.readthedocs.io/en/latest/guide/porting.html

If your code contains imports like import gtk, import gst, import glib or import gobject you are using the old bindings and you should upgrade.

pygtk supported GTK 2.0 and Python 2 only. PyGObject supports GTK >=3.0 and Python 2/3. If you port away from pygtk you also have to move to GTK 3.0 at the same time. pygtkcompat described below can help you with that transition.

I'm not an expert in python, but your code seems to need porting to PyGObject to work on Gtk3 and python3. Excuse me if I'm wrong.