[Moo] How to make addEvent for popstate?

[zipz]

Can someone explain how I can get the popstate event to be fired, with
ordinary mootools addEvent, when I use back/forward button in the
browser.

This code does not work
window.addEvent('popstate', function(event) {
        console.dir(event);
});


This code does work
window.onpopstate = function(stackstate) {
        console.dir(stackstate);
};

I don't think it's possible to add this in jsfiddle.