bug#33567: Syntactic fontification of diff hunks

[Dmitry Gutov]

On 27.12.2018 0:59, Juri Linkov wrote:

> I meant that added/removed #eeffee/#ffeeee are harder to notice,
> and really only on distant corners of the monitor.  Also looking down
> at the LCD screen from a sharp angle can see the inverted colors:
> green instead of red, and red instead of green :)

Oh, I see. IIRC, TN screens can exhibit this problem (poorer viewing 
angles), especially the older ones.

> So color choice is not the exact sciences.

It's subjective, of course.

> Since #eeffee/#ffeeee colors were tested on many users of
> GitHub/GitLab, please keep them in diff-mode and also install
> the accompanying change of refine-added/refine-removed.

OK, installed. Thanks for testing!

> GitHub only refines smaller chunks, but refining large chunks often
> helps to see real changes with code indentation, e.g. when a let-binding
> form is added and thus whitespace of indentation shifts the code block.

Of course. It's definitely useful (though it can incur some noticeable 
delay then a refined region is big enough).

What I'm saying is, reading text on a darker red background is not very 
easy or enjoyable. So I think we want to have the diff-refine-* faces to 
be as light as possible while still easy enough to discern from 
diff-added and diff-removed.

But GitHub and GitLab don't have that urgency. That's why our colors are 
lighter already.

With that in mind, I'm going to experiment with even lighter colors, 
similar to what I originally proposed, in my private config:

     (set-face-background 'diff-refine-added "#d0ffd0")
     (set-face-background 'diff-refine-removed "#ffd6d6")

Maybe try them out sometime.