> I think that Andreas is proposing doing away with this 
> invariant, or making it one-directional:
> 
> (isSubmorph(B,A)) implies (isParent(A,B)), but not 
> vice-versa.  That way, a morph can always find its world by
> traversing up the owner chain, but morphs that have been
> "closed" will not be drawn, receive mouse events, etc.

Yes, exactly. The last time this problem came up was in JIVE which actually
shows the fundamental problem more clearly. When we are in 3D there really
isn't any useful way of thinking about objects which are not in some space.
Space is infinite and therefore if some guy isn't in some space then where
the hell is he??? The only explanation for an object which is not in _some_
space is that it died away.

The same holds conceptually for Morphic if we just get a little off the
restricted boundaries of some world on the screen. If we consider the world
to be conceptually of infinite size, the same question arises with the same
answer.

Cheers,
  - Andreas