Impossible to return a value other than false or undefined from an event handler

[rformato]

Hi, I found that it's impossible to return a value other than false or undefined from an event handler.

In addition it's also useless to set a value for e.returnValue, as the event object is cloned in jQuery.event.fix

So, taking the onbeforeunload event as an example, it is not possible to return a string to show a message to the user before leaving a page.

It should be possible to fix this changing a bit jQuery.event.handle

from

if ( c[j].apply( this, args ) === false ) {
	event.preventDefault();
	event.stopPropagation();
	val = false;
}

to

if ( (val=c[j].apply( this, args )) === false ) {
	event.preventDefault();
	event.stopPropagation();
}