a:-
	new(W, dialog),
	new(N1,int_item('number 1')),
	new(N2,int_item('number 2')),
	new(TL, label('text_label', 'Result:',bold)),
	new(Label, label('test','')),
	send(W, append(N1)),
	send(W, append(N2,right)),
	send(W, append(new(OK,button('multiply!',
                         message(@prolog, echo, Label, N1?selection, N2?selection))))),
	send(W, append(TL)),
	send(W, append(Label, right)),
	send(W, default_button, OK), % Ok: default button
	send(W, open).

echo(To,6,9):-
	send(To, selection(42)).
echo(To, N1, N2) :-
	N is N1*N2,
	send(To, selection(N)).