The formview fired event itemupdating which wasn proper age for dating
Without giving a datasource to details view, because it is very easy.
When it starts to performing this task, the Mode Changing event is raised (to indicate that it's in progress) (optionally do something here).
Once that task is completed, it raises the Mode Changed event (to indicate that it's done) (optionally do something here). How could you consume the events if they don't get raised.
I'm going to guess at it, that they don't get raised initially because of nothing to do, just perform the changing of the mode.
In this example, I'm assuming that I'm displaying a set of Customer objects of some kind in a List(of Customer).
I first check to see if the List is in the Session object and, if it isn't, build it.