Currently, BCursor inherits from BArchivable privately (this is the default inheritance for C++ classes) [0]. This doesn't really make sense, sense the BArchivable class is more of an interface, and also the BeBook lists BArchivable as a mix-in to BCursor. Does anyone have the old Be headers to check this? If the inheritance is correct as is, we should add a comment, but I suspect that it's incorrect. I'm not sure, but I don't think this will affect the ABI either way, at least it's worth getting right. --Alex [0] : http://cgit.haiku-os.org/haiku/tree/headers/os/app/Cursor.h#n47