Eli,

The original _StealthProperty checked to see if it was being called on instance or class, and if it was the class it invoked __getattr__ to attempt a lookup for an enum member.  Your version does not check, but, ironically, the exception raised is AttributeError, and so Python is calling __getattr__ anyway and so finds the virtual enum member.

While this is cool, and it works, I think it's much less mysterious, magical, and downright confusing to keep the original behavior and call __getattr__ from _StealthProperty.  On the other hand, it might make somebody think, and that's always good, so I'm happy to leave it your way.