is anyone here using tms grid ? i need to get the previous (old) value of a cell on event on validate cell. how can i get it. because i need to make comparison between the old value and the new value.

is anyone here using tms grid ? i need to get the previous (old) value of a cell  on event on validate cell. how can i get it. because i need to make comparison between the old value and the new value. 

Here is the on validatecell event procedure 

procedure TfrmKasirUmum.grdMenuCellValidate(Sender: TObject; ACol, ARow: Integer;
  var Value: string; var Valid: Boolean);
begin
// 
end;

if i give the valid parameter to false, the new cell value will be revert back to the old value. i certainly believe there is a way to get the old value. but i don't know how. so please help me....

thanks in advance