The zsh-4.1.1 completion specification for the 'w3m' program
(specification attached) is incomplete.  It will only try to complete
the final argument if it's some sort of URL.  For example ..

  w3m [ -options ] http://some.url.goes.here

However, w3m can also properly be used in the following way:

  w3m file.html

... where 'file.html' is a file on disk that I want to view.  However,
zsh is not completing these cases.

How can the _w3m completion spec be changed so that both kinds of values
can validly be completed for the final argument? ... or at least so
that I can cause it to switch between the two types of completion
with some sort of keystroke.    Thanks in advance.