protected override bool ProcessCmdKey(ref Message msg, Keys keyData)//取消方向键对控件的焦点的控件，用自己自定义的函数处理各个方向键的处理函数         {             switch (keyData)             {                 case Keys.Up:                     UpKey();                     return true;//不继续处理                 case Keys.Down:                     DownKey();                     return true;                 case Keys.Left:                     LeftKey();                     return true;                 case Keys.Right:                     RightKey();                     return true;             }             return base.ProcessCmdKey(ref msg, keyData);         }