I can't help but feel like I am playing that old 80's video game "TRON" where you have to drive around in a scooter that traces a line behind you while another guy drives around in his scooter that traces a line behind him and the goal is to get the other guy to crash into one of the traced lines. That is how I feel trying to route traces without crossing another trace. Is there some trick to this other than trial and error?