No, xterm does not show such a small dialog window. But I think this does not lead into a direction in which I want. I want to "use" the existing small dialog window from "Konsole".
I decided to "solve" my problem in the following way: creating a minimal GUI-Program with just
procedure TForm1.FormActivate(Sender: TObject);
begin
sysutils.beep;
Close;
end;
and call this from my console program via TProcess or RunCommand etc.
Of course the opposite of "elegant", but if we can't find out, how FPC does it - I don't want to spend more time in such a small problem like doing a beep ;-)
Thanks again for your help.