void dgv_EditingControlShowing(object sender,DataGridViewEditingControlShowingEventArgs e)
    {
      if (dgv.CurrentCell.ColumnIndex != dt.LinkColumn.Ordinal) return;
      Button btn = new Button(); btn.Dock = DockStyle.Right;
      btn.Name = "btnOpen"; btn.Text = "..."; btn.Width = 25;
      if (!dgv.EditingPanel.Controls.ContainsKey(btn.Name))
        dgv.EditingPanel.Controls.Add(btn);
      btn.Click += new EventHandler(btn_Click);
      btn.BringToFront();
    }

   if  (dgvProjectInfo.CurrentCell.OwningColumn == dgvProjectInfo.Columns["ProjectInfoProjectCode"])
            {
                ShowProjectCodesWithButton(dgvProjectInfo);
            }
            else
            {
dgvProjectInfo.EditingPanel.Controls.RemoveByKey("btnProjectCodes");
 
            }