While I was documenting the API I noticed this discrepancy. There is a private version of BMessageQueue::IsLocked() which is non-const and there's a comment saying it should be removed in favor of the const version once we are free to break BeOS compatibility. [0] I checked the header in BeOS R5 and there isn't an IsLocked() method at all there. Furthermore MessageQueue doesn't seem to derive from any other class on either OS. So, unless I'm missing something, can we remove this method? [0] http://cgit.haiku-os.org/haiku/tree/headers/os/app/MessageQueue.h#n44