[AUCTeX] Preview and math mode

[François Poulain]

Hi,

I encounter errors when I try to use the preview LaTeX package on the
macro or environments with math mode. For example, the following file
does not compile:
%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\documentclass{article}
\usepackage[active]{preview}
\PreviewMacro[{{}{}}]{\frac}

\begin{document}

\[
  x= \frac{\alpha}{\beta}
\]

\end{document}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%

The error is:
! Missing $ inserted.
<inserted text> 
                $
l.9   x= \frac{\alpha}{\beta}

I guess this is relyed to the math mode, but I don't know how to deal
with. I tried to add @{\ensuremath} in the PreviewMacro options, but it
didn't work.

Notice that, as far as possible, I don't want to preview the entire
equation environment, but only a part of it.

Any idea?

Best regards.
François

PS: I am not subscriber of this list, please let me in CC of answers.

-- 
François Poulain <address@hidden>