Adrien's NGUI work in progress

Since I'm working on several items at the same time on NGUI, this PR can serve as a single place to review ongoing changes.
Ok that should be fine. But I am not sure about the name of the variable. It suggests it is an event to me for an instant but it is actually a constant. I am guessing from the 'My' terminology it is a service? Or is it a event name? Not clear to me in one glance. I think you have much more better context and if it makes sense then it makes sense.