在StringGrid中实现类似Combox的选择功能？

Question

procedure CellsDrawCmb(Form: TForm; StringGrid: TStringGrid; Cmb: TCombobox; ACol, ARow: integer);
//------------------------------------------------------------------------------------------------
//(1) 功  能 ：   字符串表格单元中绘制下拉框
//(2) 参  数 ：   Form-字符串表格的窗体容器类
//                StringGrid-字符串表格类
//                Cmb-下拉框
//                ACol,ARow-字符串表格行、列
//(3) 返回值 ：   无
////------------------------------------------------------------------------------------------------
var
  rectRectCell: TRect;
  pntCellPoint: TPoint;
begin
  rectRectCell := StringGrid.CellRect(ACol, ARow);
  cmb.Visible := true;
  pntCellPoint.x := rectRectCell.Left;
  pntCellPoint.y := rectRectCell.Top;
  pntCellPoint := form.ScreenToClient(stringgrid.ClientToScreen(pntCellPoint));
  cmb.Left := pntCellPoint.x;
  cmb.Top := pntCellPoint.y;
  cmb.Height := rectRectCell.Bottom - rectRectCell.Top;
  cmb.Width := rectRectCell.Right - rectRectCell.Left;
    //SendMessage(cmb.Handle,CB_SHOWDROPDOWN,1,0);
end;