public partial class Form1 : Form

{

        Point mouseOff;                          //鼠标移动位置变量

        bool leftFlag;                               //标签是否为左键

        public Form1()

        {

            InitializeComponent();

        }
}

private void Form_Load(object sender, System.EventArgs e)

{

     this.Left=(int)((Screen.PrimaryScreen.Bounds.Width-this.Width)/);

     this.Top=(int)((Screen.PrimaryScreen.Bounds.Height-this.Height)/);

}

private void Form1_MouseDown(object sender, MouseEventArgs e)

{

　　if (e.Button == MouseButtons.Left)

   {

　　　　mouseOff = new Point(-e.X, -e.Y); //得到变量的值

　　　　leftFlag = true;                              //点击左键按下时标注为true;

　　}

}

private void Form1_MouseMove(object sender, MouseEventArgs e)

{

   if (leftFlag)

   {

      Point mouseSet = Control.MousePosition;

       mouseSet.Offset(mouseOff.X, mouseOff.Y); //设置移动后的位置

      Location = mouseSet;

  }

}

private void Form1_MouseUp(object sender, MouseEventArgs e)

{

   if (leftFlag)

   {

     leftFlag = false;//释放鼠标后标注为false;

　}

}

}