Richard M. Stallman wrote:
> 	describe-frame-parameter seems to work usefully, but it has one
> 	problem: its completion list is incomplete.
> 
>     Do you mean because it iterates only over the parameters of the selected
>     frame?
> 
> I wasn't sure exactly what it does, but it certainly omits many
> standard frame parameter names.  I don't think whether the selected
> frame has a setting for a particular frame parameter ought to affect
> whether I can complete its name.
> 
>     It might also include user-defined parameters that won't be documented in
>     Info. Perhaps it should instead iterate over an explicit list of all of the
>     Info-documented (built-in) frame parameters.
> 
> I think that is the best thing to do.  Or else get that from the
> manual too.

OK, the attached version addresses all the points that have been raised:

* It defines a global list of documented frame parameters, which is
   initialized from the manual (using info, not Info-goto-node), and
   which can be augmented with user-defined parameters.

* The global list is actually an alist mapping parameters to their doc
   strings, so the doc strings are only extracted once from the manual
   and cached there.

* Completion uses the union of the documented frame parameters and any
   other parameters set in the selected frame.  The symbol at point is
   only provided as a default if it's a member of that union.

* The Info xrefs and indentation have been removed from the doc string,
   and it's been reformatted (filled) to account for that.

* Like variables, undocumented frame parameters are described as "not
   documented" and there's no link to the manual.

Enjoy!
-- 
Kevin