colour(white).
colour(red).
colour(green).
colour(blue).
colour(black).

append_colour(M, C) :-
    new(Img, pixmap(@nil, white, black, 32, 16)),
    send(Img, fill, colour(C)),
    send(M, append, menu_item(colour(C), label := Img)).

edit_graphical(Gr) :-
    new(D, dialog(string('Edit graphical %s', Gr?name))),
    send(D, append,
         new(M, menu(colour, choice,
                     message(Gr, fill_pattern, @arg1)))),
    send(M, layout, horizontal),
    forall(colour(C), append_colour(M, C)),
    send(M, default, Gr?fill_pattern),
    send(D, append, slider(pen, 0, 10, Gr?pen,
                           message(Gr, pen, @arg1))),
    send(D, append, button(apply)),
    send(D, append, button(restore)),
    send(D, append, button(quit, message(D, destroy))),
    send(D, default_button, apply),
    send(D, open).

attributedemo :-
    send(new(P, picture('Attribute Demo')), open),
    send(P, display, new(B, box(100, 100)), point(20, 20)),
    send(P, display, new(E, ellipse(100, 50)), point(150, 20)),
    send_list([B, E], fill_pattern, colour(white)),
    new(C, click_gesture(left, '', double,
                         message(@prolog, edit_graphical, @receiver))),
    send(B, recogniser, C),
    send(E, recogniser, C).