// <summary>

         /// 设置透明按钮样式

         /// </summary>

         private void SetBtnStyle(Button btn)

         {

             btn.FlatStyle = FlatStyle.Flat;//样式

             btn.ForeColor = Color.Transparent;//前景

             btn.BackColor = Color.Transparent;//去背景

             btn.FlatAppearance.BorderSize = ;//去边线

             btn.FlatAppearance.MouseOverBackColor = Color.Transparent;//鼠标经过

             btn.FlatAppearance.MouseDownBackColor = Color.Transparent;//鼠标按下

         }