in the terminology of that method call: When children (1) are added, they will actually become visible immediately after the add (so events are needed). Their children(2) however are still invisible (as their parents=marked with 1) are still collapsed. That's what i meant.
If at a later point in time, the 1 get expanded, the nodes underneath (marked with 2) will show fine (even though at the time of insertion no events were generated for them).
let me pm you my number if u want to discuss offline.