ExtJS : handling browser exit event (click on cross-exit)

I think I have found a solution. I haven't tested it on IE but it seems to be working on Firefox :

Ext.EventManager.on(window, 'beforeunload', function() {
    alert('cross-exit tab click AND cross-exit browser click');
});

Ext.EventManager.on(window, 'unload', function() {
    alert('cross-exit tab click');
});

PS : Thank you exhuma for having edited the question ;)

This thread might shed some insight: http://forums.devarticles.com/javascript-development-22/how-to-stop-browser-from-closing-using-javascript-8458.html

I haven't given this solution a test-run yet. But it seems possible.

Here's a more in-depth discussion on the onbeforeunload event handler. http://bytes.com/topic/javascript/insights/825556-using-onbeforeunload-javascript-event

And then there's always quirksmode. Unfortunately the load/unload events are not yet covered by quirksmode. As stated on the page:

I haven’t tested the load and unload events yet; they’ll be added to the table later on.