QuadMenu Snippet to Fix Sub Search

<!-- Code goes in "quadmenu/lib/frontend/walker/class-quadmenu-item-search.php" (line 78) -->
<!-- Insert one line "do action" between "endforeach" and ?> -->
            <input type="hidden" name="post_type" value="<?php echo esc_attr( $search ); ?>">
            <?php
            endif;
            endforeach;
do_action('sub_search_fields', $this->item );
  ?>
    </form>
        <?php
        return ob_get_clean();
    }
}