RE: custom: how do I augment an option?

[Drew Adams]

> > also see below (sneak preview: customize is broken :-).
> 
> Please, don't just tell us here.  `M-x report-emacs-bug', if 
> you think Emacs code is broken.  That's the only real hope
> (however slim it might be in some cases) of getting something fixed.
> 
> In all likelihood (my guess), if "customize" does not seem to 
> do the right thing in this particular case it is not because
> Customize is broken but because the programmer who coded this
> particular user option did not do the right thing.
> Those are not the same thing.  And the devil is in the details.
> So provide the details to Emacs Dev by reporting a bug.

BTW, the doc string and source code comments seem to be an admission that there
are some remaining problems.  They suggest that this option is complex and is
not necessarily for most end users to fiddle with.  IOW, this is not your
typical option.

In the doc string:

 Don't touch this variable unless you really know what you're doing.

In the code comments:

 ;; Guess this one shouldn't be easy to customize...
...
 ; Fixme: improve this