[XeTeX] Vowel placement problem with XeLaTeX/Ezra SIL

[Efraim Feinstein]

Hello list,

I've found XeLaTeX, in combination with the Ezra SIL font, to be a very 
good way to typeset pointed Hebrew.  Most of the time, it works 
flawlessly and produces high quality output.

I found what is probably a bug in the handling of HEBREW POINT QAMATS 
QATAN (Unicode 4.1+, 05C7) in combination with HEBREW POINT DAGESH OR 
MAPIQ (Unicode 05BC).  Namely, the dagesh mark appears offset when 
combined with qamats qatan, but not when combined with other vowels or 
alone.

A minimal XeLaTeX file that demonstrates the problem is attached below.  
It requires the Ezra SIL font 
<http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&id=EzraSIL_Home> 
and the SBL Hebrew font 
<http://www.sbl-site.org/educational/BiblicalFonts_SBLHebrew.aspx>.

The file shows, rendered in Ezra SIL and in SBL Hebrew, the word "כל" (kol).
 From right to left:
Word with no vowels
Word with dagesh (renders in the correct position in the kaf)
Word with dagesh and qamats gadol (both render in the correct position)
Word with only qamats qatan (renders in the correct position)
Word with dagesh and qamats qatan (dagesh renders offset, qamats qatan 
is in the correct position).

When typeset with Ezra SIL, the bug is present in the last (leftmost) 
word; when typeset with SBL Hebrew, it renders correctly.  This led me 
to believe that the problem is in the font, but, other applications that 
support pointed Hebrew don't render it in the same incorrect way.  I've 
reproduced the bug occurs in the versions of XeTeX in TeXLive 2007 and 
2008 under Debian Linux, TeXLive 2007 under Mac OS X (I haven't tried 
2008), and MikTeX 2.7 under Windows.  It displays the same way 
independent of which PDF reader I choose.

Thanks in advance for any help you can offer,
Efraim Feinstein
feinst at fas.harvard.edu

--- BEGIN qqtest.tex ---
\documentclass[12pt]{article}
\usepackage{fontspec}
\usepackage{bidi}
\newfontfamily\ezra[Script=Hebrew]{Ezra SIL}
\newfontfamily\sbl[Script=Hebrew]{SBL Hebrew}
\begin{document}
\setRL
\noindent \ezra
כל כּל כָּל כׇל כׇּל  \\
\sbl
כל כּל כָּל כׇל כׇּל
\end{document}

--- END qqtest.tex ---