Defining new tabs in the developer console
==========================================

The tabs are top-level packages inside 'interface/'.

Each package used as a tab must have a class Interface, instantiatable
with no arguments, with an attribute 'widget' that is a Gtk widget to be
placed in the tab. That's it.

Tabs are automatically run under the GLib main loop, dbus-python is set up
to use it, and the shared dbus-python session-bus connection is expected to
exist.