Re: Mixed L2R and R2L paragraphs and horizontal scroll

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sat, 30 Jan 2010 17:36:04 +0100
> From: martin rudalics <rudalics@gmx.at>
> CC: emacs-devel@gnu.org, emacs-bidi@gnu.org
> 
>  > Note that the display of the second line in the leftmost window did
>  > not change, and as result, the amounts of horizontal scroll in the 1st
>  > and the 2nd lines are different.  This is unlike in the current
>  > unidirectional display, where all the lines are always hscrolled by
>  > the same amount.
> 
> What should `window-hscroll' return in that case?

Why should it change from what it returns now?  Its doc string says:

   Return the number of columns by which WINDOW is scrolled from left margin.
   WINDOW defaults to the selected window.

So if the window is scrolled from the left margin, either because
point is on a L2R line on a column that's beyond the window's right
margin, or because the user scrolled with "C-x <", it will return the
amount of scroll as it does today.  If the window is scrolled from the
right margin, it could return a negative value, I suppose.  Or we
could have a separate function for that.  It really depends on what
the users of window-hscroll do with the value.

Or are you saying that we should scroll the R2L lines to the right by
as much as we scroll the L2R lines to the left?  That is, are you
saying we should display the last example as


      +---------+---------+-------------------+
      |$ijk     |abcdefgh$|abcdefghijk        |
      |     KJI$|$HGFEDCBA|        KJIHGFEDCBA|
      |         |         |                   |
      +---------+---------+-------------------+

Is this what you are suggesting?