With an instance of PatchArchiveClient openInWorld, I attempt to change
the class from SystemWindow subclass: #PatchArchiveClient 
To
Model subclass: #PatchArchiveClient 
When I do this I get the white screen of death (The WSoD doesn't appear
to produce an error log and I haven't figured out how to debug in this
situation.) It shows a
***system error handing failed ****
Original Error: Message not understood PatchArchiveClient>>full bounds.
   Debugger Error: Message not understood
PatchArchiveClient>>isDockingBar:[]in
DebuggerClass>>openOn:context:label:conents:fullView:{[:ex | self
primitiveError: 'Oringinal error:' , title as......

It makes sense that PAC would no longer understand fullBound once it's
changed from System Window to Model.  The problem doesn't occur when I
do not have PatchArchiveClient open, so this isn't a big deal.  I'm
reporting it because in Squeak I hope that I can change objects on the
fly with nothing worse happeing than a Debugger Window.  Wouldn't expect
that anywhere else, course.  Maybe changing the inheritence structure is
just going too far?

(This was I Squeak3.8a-63905.unstable-image but the same sort of thing
happens in Squeak3.7g-5976.image.  I'm runing Win XP Pro. )