def on_sync_ended(self, sender, backend_id):
        """
        If the backend has stopped syncing tasks, update the state of the
        Gtk.Spinner

        @param sender: not used, here only for signal callback compatibility
        @param backend_id: the id of the backend that emitted this signal
        """

        if backend_id == self.backend.get_id():
            self.spinner_set_active(False)