[auctex] Change localy the behaviour of "format environment" and friends

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

Hello all,

Often, when I'm done with a tex file, I use format environment on the 
document environment. In 99.99% case, I get the result I want. Except 
with the environment tikzpicture.

Lines ending with a semicolon like

\draw (0,0) -- (1,1);
\draw (1,1) -- (2,2);

are formatted like

\draw (0,0) -- (1,1); \draw (1,1) -- (2,2);

Is it possible to change this behaviour only inside tikzpicture 
environment?

Thanks in advance.

-- 
Christophe