Hi,

I think this is an old bug, presumably since ProtoObject was introduced (and presumably because ObjectTracer was used in
the process).

If you ask Class for its subclasses (or if you inspect it) you see that ObjectTracer class is listed along with
ProtoObject class, although ObjectTracer's superclass is ProtoObject.
This can lead to some funny bugs if you try to write some hierarchy traversing code.

Cheers,
Florin