@Override
  protected void paintVertical(Graphics g, Dimension size) {
    for (int i = 0; i < SIZE; i++) {
      g.drawLine(i + SIZE, 0, i + SIZE, size.height);
      g.drawLine(0, i, FULL_SIZE, i);
      g.drawLine(0, size.height - i - 1, FULL_SIZE, size.height - i - 1);
    }
  }
@Override
  protected void paintVertical(Graphics g, Dimension size)