protected function plugin_extend_coursemodule_standard_elements() {
        $callbacks = get_plugins_with_function('coursemodule_standard_elements', 'lib.php');
        foreach ($callbacks as $type => $plugins) {
            foreach ($plugins as $plugin => $pluginfunction) {
                // We have exposed all the important properties with public getters - and the callback can manipulate the mform
                // directly.
                $pluginfunction($this, $this->_form);
            }
        }
    }