It would be very nice if someone would want to try to check about imlib2 and it's use by tint2. I have installed fbpanel at pclinuxos openbox for the future public release, but it's not fully satisfactory, because fbpanel is not developed anymore. So I'll leave both in pclinuxos openbox.
tint2 does not bring this problem in my other usual distribution, where I launch volumeicon with the autostart.sh file as well. In case someone would ask : the number versions of tint2 and imlib2 of archlinux and pclinuxos are exactly the same.