Is it possible? If it is, it's not obvious in any way, nor documented in the manual.
I think that would be an interesting feature if it currently lacks it. I don't really know, but I think it wouldn't be so much of a huge thing to implement the possibility of running commands such as "
openbox-command menu-id-whatever" to make a given menu pop-up; or "openbox-command nexdesktop" so a script could move the view to a different desktop (but perhaps it can be done with...