bug#35721: 27.0.50; Strange Arabic shaping behavior

[Eli Zaretskii]

> From: "Basil L. Contovounesios" <contovob@tcd.ie>
> Cc: Khaled Hosny <dr.khaled.hosny@gmail.com>,  <behdad@behdad.org>,  
> <handa@gnu.org>,  <35721@debbugs.gnu.org>
> Date: Thu, 16 May 2019 21:54:10 +0100
> 
> The issue that prompted this report, however, is the alternating
> toggling of certain character compositions while typing in a separate
> part of the buffer (steps 9 and 10 in the OP), where no face change is
> involved.  I'm sorry for not making this clearer from the outset.
> 
> If you think this is unsurprising behaviour given the display engine's
> current implementation, I don't mind if you close this issue.

I'm quite sure it is the result of how the display of complex scripts
is implemented.  However, ...

> Otherwise, perhaps either this issue can be retitled, or I can submit a
> new issue focussing only on that part of the OP.

... I think it would be best to file a new bug report, which is _only_
about the above-mentioned alternations in display of composed
characters, with specific examples only for that issue.  Then these
examples could be analyzed, and either (1) we find some bug that will
then be fixed, or (2) we conclude that these are artifacts of the
current implementation of the display engine, and make this a wishlist
bug report.

Thanks.