protected function get_all_groups($courseid) {
        global $CFG;
        require_once($CFG->libdir . '/grouplib.php');

        if ($courseid != $this->allgroupscourseid) {
            $this->allgroups = groups_get_all_groups($courseid, 0, 0, 'g.id, g.name');
            $this->allgroupscourseid = $courseid;
        }
        return $this->allgroups;
    }