Thierry,<br>I didn't see whether you ever solved the Metapost exit code 256 problem or not&nbsp;so I thought I would post my solution. I had to make sure my PATH variable included the directory where teTeX binaries were installed. In my case (Therion 
0.3.9 on a more or less out-of-the-box slackware 10.2 machine), I simpled added&nbsp; the following line to ~/.zshrc, my login script:<br>PATH=/usr/share/texmf/bin:$PATH<br>That made everything run swimmingly for me. Good luck!
<br><br>Sincerely,<br>Jonny