RE: ediff refinement issues

[Drew Adams]

> Yes of course.  I want ^;;; or ^# to act as whitespace in this case.

AFAIK, there is no way to tell ediff to ignore differences in text that matches
an arbitrary regexp.  IOW, it ignores only whitespace when you tell it to ignore
whitespace. ;-)

Ignoring whitespace is a built-in feature of ediff.  IIUC, what you are asking
for is not a feature provided by ediff.

I have long wanted the ability to tell ediff to ignore (i.e., consider as the
same) all matches for a given pattern.  AFAIK, that feature is waiting to be
implemented. ;-)

> One issue is that I want only ^;;; or ^# to be treated as whitespace.
> Not ;;; or # in the middle of text.

Neither case will ever be treated as whitespace.  Such patterns do not represent
whitespace.

> It is really simple.  I don't see why I should have to look at
> highlighted spurious things when all I did was fill a paragraph.

Filling a paragraph typically changes more than whitespace.

;;; aaa bbb ccc ddd
;;; eee

and 

;;; aaa bbb ccc
;;; ddd eee

wrt more than whitespace.  Ediff shows you the difference.
`;;;' is not whitespace.

> But if you had an unfilled paragraph... and ediffed the
> filled and unfilled versions, you might understand.

They differ wrt non-whitespace text, namely, the comment chars.

AFAICT, in what you describe:

1. Ediff is acting as advertised.
2. There is no option/command to have ediff ignore differences in text that
matches a pattern other than whitespace.

Again, maybe someone else can help more.