//渐渐的消失

    for (int iNum = 10; iNum >= 0; iNum --)

     {

        //变更窗体的不透明度

        this.Opacity = 0.1 * iNum;

        //暂停

         System.Threading.Thread.Sleep(100);

     }

     //渐渐的显示

    for (int iNum = 0; iNum <= 10; iNum ++)

     {

         //变更窗体的不透明度

        this.Opacity = 0.1 * iNum;

        //暂停

         System.Threading.Thread.Sleep(100);

     }