Where is the display engine code?

On Wed, Feb 23, 2022 at 3:58 PM Eli Zaretskii <eliz@gnu.org> wrote:

> > From: Lars Ingebrigtsen <larsi@gnus.org>
> > Date: Wed, 23 Feb 2022 14:18:46 +0100
> > Cc: Kip Coul <kipcoul@gmail.com>, Stefan Kangas <stefan@marxist.se>,
> >  Jack Morrison <JackMorrison1@gmail.com>, 18548@debbugs.gnu.org
> >
> > So I don't know whether anything can or should be done in this case.  I
> > think that (perhaps) a reasonable default would be to remove that
> > mapping -- whitespace-mode (by default) marks TAB characters anyway with
> > a face, so having a » in addition is somewhat superfluous.  On the other
> > hand, it's been like this forever, so perhaps we should just document
> > the quirk instead.  Or add a defcustom to allow for easier toggling, and
> > the defcustom would then also act as documentation for this.
> >
> > Any opinions?
>
> I think the only way to fix this (and I agree that it's a marginal use
> case) is to introduce some special syntax into display-table notation,
> and then teach the display engine to ignore the TAB when whatever is
> before it in the display-table entry already ends at a tab stop, and
> the display-table entry has that special syntax.
>
> Not sure if it's worth the hassle.
>
> In any case, most of the implementation should be in the display
> engine, because that's where the TAB display is implemented in Emacs.
>