type
MyStringGrid = class(TStringGrid)
private
....
protected
function SelectCell(ACol, ARow: LongInt): Boolean; override;
.....
end;
function TMyStringGrid.SelectCell(ACol, ARow: LongInt): Boolean;
begin
result := false;
if ACol = 7 then Col := 8 else result := inherited selectcell(acol, arow);
end;
....