[XeTeX] xunicode, tipa (again) plus amsmath

[Alan Munn]

Hi, a while ago, Ulrike posted an nice way to allow legacy tipa code  
to be used with xelatex.  Unfortunately I've encountered a problem: it  
doesn't work inside math mode.  Is there a way to fix this?  Thanks

Alan


% !TEX TS-program = XeLaTeX

\documentclass{article}
\usepackage{amsmath}
\usepackage{xltxtra}
\newfontfamily{\ipafont}{Doulos SIL}
\def\useTIPAfont{\ipafont}
\newenvironment{ipa}{%
  \let\stone\TIPAstonebar
  \let\tone\TIPAtonebar
  \setTIPAcatcodes\activatetipa
  \csname useTIPAfont\endcsname
  }{}
\begin{document}
\textipa{RPAQIOE2} % This will give you correct phonetic characters
\begin{ipa}
RPAQIOE
\end{ipa}
$\text{\textipa{RPAQIOE2}}$ % unfortunately this doesn't
$\textipa{RPAQIOE2}$ % and neither does this
\end{document}
-- 
Alan Munn
amunn at gmx.com