I'll let someone else find the laws but it's generally not a good idea to cross in cross walks. The reason is that cars aren't looking for bikes in cross walks, they're looking for people. I've had close calls with other cyclists crossing at cross walks when I'm riding my bike. Something is messed up with that equipment if it's giving the signal to cross at the same time as left arrow though. It looks you could position yourself to the right of through-traffic so I don't even see why you think it's beneficial to use the cross walk.