Hi Mélodie,
I'm running the live CD now. I like the panel at the bottom and can even move it to the top and back to the botton without a problem. I did have to adjust the top desktop margin down from 23. Also, I still got the warning about 4 desktops in the .xsession-errors file, but it went away after I logged out and logged back in. I'll install this to VirtualBox next and give it run. It looks like you're almost there. 
Jeff
Hi Jeff,
I still need to figure out for the 4 desktops. I'll reduce to 2 and we will see what goes on at first login in live. The progress is to be credited to Parnote who gave me the idea to externalise scripts additionnally to delay the start for pcmanfm and lxpanel.
You can look at theses scripts in /usr/local/bin and how they are started in /home/guest/.config/openbox/autostart.sh
The move to top and background without pain is due to... if I remember, I removed an applet that was not available.
Best regards,
Mélodie