my $window = call_on_obj(
    Gtk2::Window->new( "toplevel" ),
    [ signal_connect   => ( delete_event => sub { Gtk2->main_quit } ) ],
    [ set_title        => "Test" ],
    [ set_border_width => 15 ],
    [ add              => call_on_obj(
        Gtk2::Button->new( "Quit" ),
        [ signal_connect => ( clicked => sub { Gtk2->main_quit } ) ],
    ) ],
    [ 'show_all' ],
);