Try this link. I first met openbox-menu through Bonsai at PCLOS two and a half years ago. I think mimas wrote it in C++. Semplice uses something different called Alan based on python, which from memory I found to be very clumsy.
EDIT - maybe obam in perl is what you are looking for.
Thanks for the link. Bookmarked it for safekeeping. Okay, mimas is the one who originally added the icons capability to Openbox's menu.
You're right. Semplice uses alan. Can't remember whether it's perl, python, bash or whatever. But, yeah, I spent hours tracking down all the pieces of it scattered throughout the system and became ever more confused.
After bookmarking the link to mimas's work, I rediscovered the link I already had for
obmenu-generator. I remember you pointed that one out a while back and asked if anyone is versed in perl. Have you looked at it?