protected function render_add_button($courseid) {
        global $CFG;

        $button = \html_writer::tag('button', get_string('addrule', 'tool_monitor'), ['class' => 'btn btn-primary']);
        $addurl = new \moodle_url($CFG->wwwroot. '/admin/tool/monitor/edit.php', array('courseid' => $courseid));
        return \html_writer::link($addurl, $button);
    }