c＃ADO，Sql server从datagriview

Question

我已经下载了一个c＃sql server ADO项目，我很难理解this.dataGrid1.UnSelect(this.dataGrid1.CurrentRowIndex);的部分内容 我没有看到Unselect函数的函数定义，我无法弄清楚它是用户定义的函数还是buildin函数。 错误消息是Systems.Windows.Forms.DataGridView不包含＆＃39; Unselect＆＃39;的定义。没有扩展方法＆＃39;取消选择＆＃39;接受Sytems.Windows.Forms.DataGridView类型的第一个参数可以找到（你是否缺少使用指令或汇编引用？）

private void btFirst_Click(object sender, System.EventArgs e)
     {
        if((currManager!=null)&(currManager.Count>0)) 
        {
          fnClearStatusbarPanel2();
          fnSelectUnselectLastFirstRow(0);
          //set the position at the first record 0
          currManager.Position=0;
          //enable pushbuttons Next, Last
          fnEnableDisableButtons(this.btNext,this.btLast,"", true);
          //disable pushbuttons First, Previous
          fnEnableDisableButtons(this.btFirst, this.btPrevious,"First record...",false);            
          //display record numbers in the StatusBar
          fnDisplayRecordNumbers(); 
        }
     }

     private void fnSelectUnselectLastFirstRow (int posi)
     {
        //unselect the last selected/highlighted row    
        this.dataGrid1.UnSelect(this.dataGrid1.CurrentRowIndex);

        //select the last or first row
        this.dataGrid1.Select(posi);
     }