Uh, oh. I think I found the bug, and it was a *really stupid bug*. The list of GUI_PLUGINS was empty... so there was no plugin class that was inherited.
I'm embarrassed to have wasted your time that way. However I learned a lot about new-style classes and so on, so for me it was a learning experience nonetheless. Really sorry for wasting your time. I should use a debugger, I know. : ( Thanks a lot for your patience, M. -- http://mail.python.org/mailman/listinfo/python-list
