In case you haven't run into it there is a bug in derived classes. Member variables of base classes are accessable in derived classes as they should be. However if a derived class is used as a base class for a new one then the variables are duplicated a second time resulting in the size of the class being wrong. And access to the derived classes variables will have the wrong offset.
This has been fixed for the next alpha update.
Recursion at its finest came back to bite me ;)
Paul.