Point mouseOff;//鼠标移动位置变量         bool leftFlag;//标记是否为左键         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;             }         }