panel边框设置为none

双击panel进入代码，例如

//重绘panel_sign边框
private void panel_sign_Paint(object sender, PaintEventArgs e)
{
	ControlPaint.DrawBorder(e.Graphics, panel_sign.ClientRectangle, Color.LightGray, ButtonBorderStyle.Solid);
	/*ControlPaint.DrawBorder(e.Graphics, panel_sign.ClientRectangle,
			Color.Pink, 1, ButtonBorderStyle.Solid, //左边
			Color.Pink, 1, ButtonBorderStyle.Solid, //上边
			Color.DimGray, 1, ButtonBorderStyle.Solid, //右边
			Color.DimGray, 1, ButtonBorderStyle.Solid //底边
	 );*/
}