private void lvwTitle_MouseDown(object sender, MouseEventArgs e)    {      Point curPos = this.lvwTitle.PointToClient(Control.MousePosition);      ListViewItem lvwItem = this.lvwTitle.GetItemAt(curPos.X, curPos.Y);      if (lvwItem != null)      {        lvwItem.Checked = !lvwItem.Checked;        lvwTitle.Refresh();      }           }