Well, focus=width doesn't work in my test file:

\setupinteraction
 [state=start,
  focus=fit,
  openaction=FitWidth]

\starttext
\goto{link}[page(5)]
\dorecurse{10}{\input knuth \page}
\stoptext



I also checked
http://wiki.contextgarden.net/Reference/en/setupinteraction
and no focus option

-- 
Best Regards
Chen