Mine

    def __set_tooltip (self):
        if not globalvar.applier:
            return

        try:
            schema = globalvar.applier.get_schema ("/schemas" + self.key)
            if schema:
                globalvar.tooltips.set_tip (self.checkbutton,
                                            " ".join (schema.get_long_desc ().split ()))
        except gobject.GError:
            print >> sys.stderr, "Warning: Could not get schema for %s" % self.key