Re: Mixed L2R and R2L paragraphs and horizontal scroll

 >> Inconvenient for the user.  Why scroll something out of view if there's
 >> no urgent need to do so.  (Although a similar argument could be made for
 >> pure LR text as well
 >
 > Exactly!  So perhaps we should adopt this design,

Which one?

 > as it doesn't make
 > things worse and does not require additional interfaces (such as
 > `window-RL-hscroll').
 >
 >>  > That's what would happen if the second line was
 >>  > displayed at the left margin, like this:
 >>  >
 >>  >       +---------+---------+-------------------+
 >>  >       |$ijk     |abcdefgh$|abcdefghijk        |
 >>  >       |$IJK     |$HGFEDCBA|        KJIHGFEDCBA|
 >>           ^^^^^^^^^
 >>  >       |         |         |                   |
 >>  >       +---------+---------+-------------------+
 >>
 >> I fail to understand the marked text in your example.
 >
 > In the current unidirectional display, where text is always displayed
 > in its logical (i.e. reading) order, the second line would have been
 > displayed as "ABCDEFGHIJK", flushed to the left margin.  Then when the
 > line above it is scrolled to show just "$ijk", so would be the second
 > line, and it would display as "$IJK".

I still don't get you.  In your earlier examples capitalized text always
showed reverse as KJI and not as IJK.  But I also fail to understand why
there's no text on the right of this.  So maybe you meant something like

       +---------+---------+-------------------+
       |$ijk     |abcdefgh$|abcdefghijk        |
       | KJIHGFE$|        $|        KJIHGFEDCBA|
       |         |         |                   |
       +---------+---------+-------------------+

(no text in the second line of the second window) instead?

 > My point was that the bidirectional display conceptually does the
 > same, except it reverses the characters and flushes them to the right.

I suppose this would apply regardless of the strategy chosen.

martin