(my $window = Gtk::Window->new("toplevel")) ->signal_connect(delete => sub { Gtk->exit(0); return }) ->set_title("Test") ->border_width(15) ->add($btn) ->show; #### my $window = Gtk::Window->new("toplevel"); for ($window) { $_->signal_connect(delete => sub { Gtk->exit(0); return }); $_->set_title("Test"); $_->border_width(15); $_->add($btn); $_->show; }