private void button1_MouseEnter(object sender, EventArgs e)
        {
            //测试鼠标进入按钮时发生的动作事件
            //mounseenter
            button1.BackColor = System.Drawing.Color.Blue;
        }

        private void button1_MouseHover(object sender, EventArgs e)
        {
            ///测试鼠标进入按钮静止一些时间会发生mousehover
            MessageBox.Show("mouse进入button1 好一些时间没作什么活");
        }

        private void button1_MouseDown(object sender, MouseEventArgs e)
        {
            //mousedown测试鼠标按下发生
            MessageBox.Show("在button1上正按下mouse"); ;
        }