Thx for the reply, but it does not fix the problem.
We are testing with the usercontrol (ascx) and for example, I need to change the bgcolor of the control based on the number passed in. It is OK when the tree has been binded. When that happens ContentContainer is not null, but if I am binding and if I am trying to perform something on the usercontrol inside the node using ContentContainer.Find..., it will throw null exception, because the ContentContainer is null. The question is, when does the ContentContainer gets created and which event comes after that, so that I can override the handler for that event and do what I need to do with the control inside the ContentContainer.