[chirp_users] Trying chirpw with python3

I am trying to use the py3 branch of chirpw, because Fedora Linux is in the process of deprecating python 2. Mostly it is going well, but when I try to export to a CSV file, I get this error message:

There was an error during export: 'gi.repository.Gtk' object has no attribute 'Tooltips'

The error appears to originate in chirp/ui/importdialog.py around line 302:

tips = gtk.Tooltips()

Unfortunately, I don't know enough python to understand why this error is happening.

Does anyone have a suggestion about how to use chirpw with python 3?

Steve