在窗體的Paint事件中加入以下代碼

// 重繪窗體

private void VIEwInstanceDialog_Paint(object sender, PaintEventArgs e)


...{

// 為窗體中畫線

Graphics line = CreateGraphics();


line.DrawLine(new Pen(Color.Gray, 1), new Point(10, 280), new Point(Width - 20, 280));

line.DrawLine(new Pen(Color.White, 1), new Point(10, 281), new Point(Width - 20, 281));

}