[OS X TeX] \wideparen doesn't show up

[André Bellaïche]

Compare both files (if you have the mtpro fonts):

\documentclass[twoside]{book}
\usepackage{yhmath} 
\begin{document}
$$
\wideparen{a \ast b}
$$
\end{document}

There is a arc above  a * b

\documentclass[twoside]{book}
\usepackage{yhmath} 
\usepackage{mtpro2}
\begin{document}
$$
\wideparen{a \ast b}
$$
\end{document}

With mtpro2 loaded, the arc doesn't show anymore. Could it be that there is some mechanism in mtrpro2 whoch disable \wideparen ? 

The definition ot  \wideparen in yhmath is shown here:

> \wideparen=macro:
->\protect \mathaccentV {wideparen}3F3.
l.5 \show\wideparen
                   
André Bellaïche