3b works like ya said in OS X (see att. img).  no error messages. file/source caused poser to crash.  file/close caused machine to do something for approx 10 sec, then it closed.  no changes seen in box vertices in doc window.  dunno how to save changes, if possible at this point.

there are sevl. softwares for uv unwrapping - uv layout, unwrap 3d, blender et al.
AFAIK uvmapper pro doesn't do that, but I can't verify, as cox never bothered to
provide an OS X version.