Re: bidi-display-reordering is now non-nil by default

[Eli Zaretskii]

> From: Chong Yidong <address@hidden>
> Cc: address@hidden, address@hidden,
>         address@hidden
> Date: Fri, 05 Aug 2011 17:54:54 -0400
> 
> Still, it seems better not to change Gnus to proactively insert LRM
> characters, but leave it to those users who care to customize it as
> necessary.

I don't think this is a good idea.  It requires users to know too much
about the reordering algorithm.  From this discussion you may conclude
that those who need it will have that knowledge anyway, but I think
this conclusion would be wrong: the participants of this discussion
who argue for usage of these characters are not typical users.

> This has the advantage of avoiding inserting the insertion of excess LRM
> characters by default.
> 
> The disadvantage, of course, is that it requires some extra
> knowledge from users, but we can handle this by adding a note to the
> docstring.

We have no hope of giving precise instructions about this in a doc
string.  All we can do is mention those characters.  Users who don't
know about the UBA will have hard time finding where to insert them by
trial and error.  I can tell you from my experience of writing
TUTORIAL.he that it took _me_ a few trials and errors to know which
directional control to insert in some cases.

Anyway, I don't understand the opposition to using directional
controls, here and elsewhere.  We already use special characters, like
spaces and '[..]' above, to make the summary line more visually
appealing.  Why are LRM and RLM different?  They are just characters,
and they are barely visible.  If even the current thin-space
appearance is deemed too visible, we could change the default value of
glyphless-char-display to make them not visible at all.  (I think
Stefan said we should do that, see the discussion referenced below).
On top of that, summary buffers are rarely traversed by users, so the
chances they will pay attention are slim at best.  So what is the
reason(s) for such opposition?  I just don't get it.

Btw, a similar discussion about buffer names that include R2L
characters ended up concluding that we should use RLM/LRM controls to
make FOO<2> etc. display correctly in all kinds of context, see the
thread that started here:

  https://lists.gnu.org/archive/html/emacs-devel/2011-06/msg00712.html

In that thread, _I_ had my reservations, and others, including Stefan,
convinced me that using directional controls is TRT.  How is this case
different?