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