private void Form1_MouseDown(object sender, MouseEventArgs e)    {      // get mouse position relative to Screen      int offsetFrom_ScreenOrigin_X = Cursor.Position.X;      int offsetFrom_ScreenOrigin_Y = Cursor.Position.Y;      // set mouse position relative to screen, e.g. at pixel (100, 100)      Cursor.Position = new Point(100, 100);      // get mouse position relative to a control (must be in any mouse event function)      int offsetFrom_Form1Origin_X = e.X;      int offsetFrom_Form1Origin_Y = e.Y;      // set mouse position relative to a control, e.g. at pixel (100, 100)      Cursor.Position = this.PointToScreen(new Point(100, 100));    }