Created attachment 423398 [details]
There is a rendering bug on the tabs in authconfig-gtk. See screenshot.
I'm sorry but this is definitely not a bug of the authconfig package itself. This must be something wrong with gtk, pygtk or other components on the system. Do you see the same glitches in other GTK/PyGtk applications?
No, this is why I filed the bug against authconfig-gtk... on all other GTK notebooks I have seen, the active tab has a transparent-filled blue selection ring and there is no "box" around the text of the inactive tabs...
This was caused probably by the move from glade2 to glade3. There are superfluous event boxes. I've fixed it in the upstream hg repo.