* 764続き *

  protected override void WndProc(ref Message m)
  {
    base.WndProc(ref m);
    const int WM_PAINT = 0xF;
    switch (m.Msg)
    {
      case WM_PAINT:
        using (Graphics g = CreateGraphics())
        {
          using (Pen pen = new Pen(BorderColor))
          {
            Rectangle rect = ClientRectangle;
            rect.Width -= 1; rect.Height -= 1;
            g.DrawRectangle(pen, rect);
          }
        }
        break;
    }
  }
}