If it was intended by Foo's author that Borg::comment should be overridden, then no one should be writing code that uses Foo and also tries to by-pass Foo's version of the comment method.

If the overriding was accidently, then either Foo's author can rename Foo::comment, or can provide a wrapper method so that the functionality of Borg::comment is made available under a different name.

This is an interesting technical point, but I would imagine that a situation like this would rarely occur in practice. Nonetheless, I'll add information about this to the POD. Thanks.

Update: Actually, this applies to more than just overridden methods. You can't use any fully-qualified method calls to inherited foreign classes. But then again, you shouldn't need to.