protected function move_files_in_hints($questionid, $oldcontextid, $newcontextid) {
        global $DB;
        $fs = get_file_storage();

        $hintids = $DB->get_records_menu('question_hints',
                array('questionid' => $questionid), 'id', 'id,1');
        foreach ($hintids as $hintid => $notused) {
            $fs->move_area_files_to_new_context($oldcontextid,
                    $newcontextid, 'question', 'hint', $hintid);
        }
    }