If a class is still referenced in code, then removed, and later filed  
back in, the former references do not point to the newly filed-in  
class, but to the obsolete former class.

This breaks (at least) the unloading and re-loading of Monticello  
packages. You have to manually recompile all methods that reference  
the class.

Would moving a class to Undeclared be a good fix for that? Or do we  
need a weak registry for removed classes to be able to efficiently  
fix up the references later?

Btw, there are two methods for detecting this situation:

	SystemNavigation default browseObsoleteMethodReferences

	SystemNavigation default browseObsoleteReferences

One is much faster than the other, both have identical results for  
me. Do we need both?

- Bert -