public function print_header($headingstr, $summary=true) {
        global $OUTPUT, $PAGE;
        $titlestr = get_string('exporting', 'portfolio');
        $headerstr = get_string('exporting', 'portfolio');

        $PAGE->set_title($titlestr);
        $PAGE->set_heading($headerstr);
        echo $OUTPUT->header();
        echo $OUTPUT->heading($headingstr);

        if (!$summary) {
            return;
        }

        echo $OUTPUT->box_start();
        echo $OUTPUT->box_start();
        echo $this->caller->heading_summary();
        echo $OUTPUT->box_end();
        if ($this->instance) {
            echo $OUTPUT->box_start();
            echo $this->instance->heading_summary();
            echo $OUTPUT->box_end();
        }
        echo $OUTPUT->box_end();
    }