Mine

<?php

$wnd1 = new Gtkwindow();
$wnd1->connect_simple('destroy',array('gtk','main_quit'));
$button = new GtkButton();
$button->connect_simple('clicked',array($wnd2,'show_all'));
$wnd1->add($button);
$wnd2 = new Gtkwindow();
$wnd2->connect_simple('destroy',array('gtk','main_quit'));
$wnd1->show_all();
Gtk::main();
?>