Re: Arabic support

[Eli Zaretskii <eliz@gnu.org>]

> From: Kenichi Handa <handa@m17n.org>
> Date: Thu, 26 Aug 2010 10:10:05 +0900
> 
> I've just committed changes to trunk for Arabic shaping.  If
> there're any Arabic users in this list, please check the
> displaying of Arabic text.  On GNU/Linux system, you must
> compile Emacs with libotf and m17n-lib (configure script
> should detect them automatically).

Thanks.  However, today's build behaves very strangely in a GUI
session on MS-Windows.  For starters, cursor motion seems to jump
across many characters in the "Arabic" line of etc/HELLO.  For
example, typing C-f in that line, I first move one character at a time
across "Arabic", as expected, then the cursor jumps to the right paren
of the leftmost parenthesized part, again as expected, and then I see
the following strange behavior:

  . C-f moves one character to the left, to buffer position 758, as
    expected.

  . the next C-f jumps across many characters on the screen and lands
    on position 764.

  . another C-f jumps to what is reported as position 765, but on the
    screen those are several characters, maybe 5 or 6.

  . another C-f moves to the left paren at position 766, as expected.

  . yet another C-f moves to position 767, but on the screen the
    cursor jumps back into one of the characters it jumped across when
    it landed on position 765 two C-f keypresses earlier.

  . if I type C-b 4 times from this point, I enter a "trap", whereby
    typing C-b jumps between two characters, whose buffer positions
    are 764 and 765.  The only way to get out of the trap is with C-a
    or C-e or C-f.

I don't read Arabic, so I cannot really say whether any of this is
expected behavior.  (The "trap" with C-b is certainly not the expected
behavior.)  Do you see anything similar on X?