Identification of group headers and group summarie

I do need an advise how to identify group header rows and summary rows on a stringgrid (or more precisely: TDBAdvGrid) which are grouped.

I.e.
I fire "OnGetCellColor"

procedure TForm1.DBAdvGrid1GetCellColor(Sender: TObject; ARow, ACol: Integer;
  AState: TGridDrawState; ABrush: TBrush; AFont: TFont);
begin
  if (ARow = "group header") or (ARow = "Group summary") then //How can I rewrite this condition?
  begin
    //Make colors - or other things - only if the row is a group header or a group summary
  end else
  begin
    //Make colors - or other things - only if the row is NOT a group header or a group summary
  end;
end;

Any suggestions?

Anders

Please use the functions:

grid.IsNode(Row): boolean
grid.IsSummary(Row): boolean