get_window()->draw_line (get_style()->get_black_gc(), x1, y1, x1, y2);
get_window()->draw_line (get_style()->get_black_gc(), x1, y2, x2, y2);
}
get_window()->draw_line (get_style()->get_black_gc(), x1, y1, x1, y2);
get_window()->draw_line (get_style()->get_black_gc(), x1, y2, x2, y2);
}