[auctex-preview] Preview a tikzpicture environment

[Christophe Jorssen <christophe.jorssen@libre.fr.invalid>]

Hello all,

I use preview to preview my tikzpicture in a latex document (with auctex).

In the preamble, I put a

\PreviewEnvironment{tikzpicture}

It works fine, except when I have computed coordinates with $ (I suppose 
that there is a conflict with the preview of inline math).

For instance

\documentclass{minimal}
\usepackage{tikz}
\usetikzlibrary{calc}

\usepackage[active,tightpage]{preview}
\PreviewEnvironment{tikzpicture}

\begin{document}

\begin{tikzpicture}
\draw[help lines] (0,0) grid (5,5);
\coordinate (X) at (1,2);
\coordinate (Y) at (2,1);
% The problem is here
\coordinate (Z) at ($(X)+3*(Y)$);
\end{tikzpicture}
\end{document}

Any ideas?

Thanks in advance

-- 
Christophe