Shaping in VIM , in Linux vs. Solaris

[Isam Bayazidi <bayazidi at accessme dot com>]

As we're working on adding Arabic to VIM (still a work in progress with
lots of questions to be answered - note the 'vim-dev' list) we've came
across something very peculiar.

One of the guys helping with this effort is on a Solaris box

uname -a: SunOS mipo 5.7 Generic_106541-15 sun4u

notes that he's able to see certain characters that we (some on linux
others on FreeBSD) aren't. The only thing we could attribute our
short comings to is that we are using different iconv utilities (we're
all configuring with the same options, etc) the solaris guy does NOT
have liconv (GNU's version of iconv) installed though. The guy on
Solaris is able to see 'shaped' letters (Unicode FE70 - FEFF) if the
keymap encodings are simply set to those values. We all can see
(Unicode 0600 - 06FF) without a hitch. So why can't linux display
Unicode FE70 - FEFF like solaris can (same VIM code) ?

To reproduce the problem, please do the following (use VIM-6.0)

1. download the font and keymap files (add the .bdf file to your fp path)
http://www.arabeyes.org/~nadim/vim/arab_shape_bug.tar.gz
(( I didn't want to clutter the mailing-list by attaching ))

2. enable the various arabic settings
:set keymap=arabic
:set guifont=-misc-fixed-medium-r-normal--20-200-75-75-c-100-iso10646-1
:set encoding=utf-8

3. Press 'a' (note visible non-shaped letter)
Press 'q' (note BOX for shaped letter -- WRONG)
Press 'w' (note BOX for shaped letter -- WRONG)

So why is solaris able to display those shaped letters where-as
linux/FreeBSD are unable ? How to fix it ?

Awaiting your help.
                Yours
                        Isam Bayazidi

PS. Please make sure that our developer mailing list is CCed on the reply 
.. Thanks