procedure TForm1.Button1Click(Sender: TObject); 
var bmk: TBookmark; 
begin 
  DBGrid1.options := DBGrid1.options + [dgMultiSelect]; 
  DBGrid1.setfocus; 
  with DBGrid1.DataSource.DataSet do begin 
    bmk := Getbookmark; 
    DisableControls; 
    First; 
    while (not Eof) do begin 
      DBGrid1.SelectedRows.CurrentRowSelected := True; 
      Next; 
    end; 
    Gotobookmark(bmk); 
    Freebookmark(bmk); 
    EnableControls; 
  end; 
end;