When closing a root Nav, it would also send the OpenEvent to the child Navs (if it's open).
So if I close a root Nav, the OpenEvent would end up at the leaf Nav.
It makes some troubles when I try to handle the onOpen event for each nav component.

example:
http://zkfiddle.org/sample/23os1gc/1-Nav-OpenEvent-propagation

I think the close order should be reversed. At least, I close a root nav, the event won't end up at the leaf nav.