Virtual page error

I tryied to use Virtual Page:
$b->add(‘VirtualPage’)->bindEvent(‘My Cool Title’,‘click’)->set(function($page){
$page->add(‘LoremIpsum’);
});

It seems working, but console shows 500 (Internal Server Error) and log:
[04-Nov-2014 09:18:39 UTC] PHP Fatal error: Call to a member function destroy() on a non-object in /home/alf/www/hidaja/vendor/atk4/atk4/lib/VirtualPage.php on line 176

Where did you get that sample? Is it from book? Did you open a bug report ?