datagridview key down problem

private void Form1_Load(object sender, EventArgs e)
   {
       this.dataGridView1.SelectionMode = DataGridViewSelectionMode.CellSelect;
       this.dataGridView1.MultiSelect = false;
   }

   private void dataGridView1_CellLeave(object sender, DataGridViewCellEventArgs e)
   {
       if (dataGridView1.CurrentCell.RowIndex == e.RowIndex)//i.e: next or befor cell is belong to current row
       {
           //some code...
           // accept all manupulition
       }
       else
       {
           //otherwise, reject all.
       }
   }