//实现类似QQ停靠桌面上边缘隐藏的效果！
        private void timer1_Tick(object sender, EventArgs e)
        {
            System.Drawing.Point pp = new Point(Cursor.Position.X, Cursor.Position.Y);//获取鼠标在屏幕的坐标点
            Rectangle Rects = new Rectangle(this.Left, this.Top, this.Left + this.Width, this.Top + this.Height);//存储当前窗体在屏幕的所在区域 
            if ((this.Top < 0) && Win32API.PtInRect(ref Rects, pp))//当鼠标在当前窗体内，并且窗体的Top属性小于0 
                this.Top = 0;//设置窗体的Top属性为0 
            else //当窗体的上边框与屏幕的顶端的距离小于5时 
                if (this.Top > -5 && this.Top < 5 && !(Win32API.PtInRect(ref Rects, pp)))
                    this.Top = 5 - this.Height;//将QQ窗体隐藏到屏幕的顶端 
        }

   class Win32API
    {
        [DllImport("User32.dll")]
        public static extern bool PtInRect(ref Rectangle r, Point p);
    }