Re: address@hidden: highlight-changes-rotate-faces sets buffer modified flag]

[martin rudalics]

>     (2) Suppose I reset the buffer-modified flag and bind `buffer-undo-list'
>     to t as in my patch.  In this case I would not be able to undo the
>     change caused by `highlight-changes-rotate-faces' and end up with quite
>     confusing colors after an arbitrary sequence of undos and saves.
>
> Should this mode use overlays?

It does use a combination of text-properties and overlays.  On my
machine, the combined use of an after-change hook and overlays already
seems to cause a noticeable slowdown during editing.

> Should it use something the font-lock mechanism so that it can update
> when the buffer is edited?

Hmmm ... it does so, in principle, but for the reliance on the undo
mechanism.  I doubt that we can do much better.