RE: ediff refinement issues

["Drew Adams" <drew.adams@oracle.com>]

>   1) When there are only whitespace differences in normal
>      paragraphs, such as by refilling, ediff works well.  It
>      says there are only whitespace differences and does not
>      highlight any words.
> 
>      However, if the paragraphs are commented (for example,
>      with ;;; in elisp or # in shell), it highlights the ;;;
>      or the #.  it also sometimes highlights words as a side
>      effect.

I don't see that.  Maybe give a concrete example.  What I see is that whitespace
is either ignored everywhere or it is not ignored at all (toggle this with
`##').

>      I want ediff to show refilled commented paragraphs as
>      only having whitespace differences.

Are you sure that the paragraphs themselves have only whitespace differences?
You say that `;;;' is highlighted as different.  Do you mean that the `;;;' is
highlighted in both of these identical lines?

;;; commented line

;;; commented line

>   2) When I change a date like 2011-01-01, ediff highlights
>      the entire date even if I only changed one part of it.
>      For example, if I change 01 to 02, it will still
>      highlight the entire date.
>      I want it to show only the part I changed.
> 
> There are variables ediff-word-1 ediff-word-2 ediff-word-3
> ediff-word-4 that are supposed to customize this.  I tried
> them in various ways and they didn't produce the results I
> wanted.  How do you use those variables to do this?

I've never played with that, and I don't know of any command or option that
helps here, but maybe someone else can help.  Looking in the code a bit, I see
this:

1. Those are defvars, not defcustoms.
2. They are buffer-local.

So I tried this in each of two buffers that had only this, respectively:
"2011-01-01" and "2011-01-02": `M-: (setq ediff-word-1 "[:word]")'.

Then, hitting `!' showed a refinement that distinguished "2011" from the rest.
I would have expected the "01" / "02" difference to be distinguished. Maybe you
can play around a little more this way to get what you want.