GTK+ used to be imported with a regular python module, using the pygtk project.
pygtk has been dropped for GTK+3, and Gobject Introspection is used instead (kind of automatic binding from C).
So this changes a lot of things. The import is not done the same, and most of shortcut-functions of pygtk are gone and real C objects should be accessed. :'( :'( :'(