I have managed to install xbindkeys on my lubuntu 16.04 box, which I think is the correct tool for me to use to map a simultaneous left and right mouse button click to emulate a middle mouse click.
I originally thought I should do this using the openbox configuration file (I am using lxde with openbox) but couldn't find a way of doing it.
Can I do this with xbindkeys? If so how? I can't get my head around how the system works as I am totally unfamiliar with it.