The current use for middle click (air) doesn't make that much sense to me. It would be much more obvious to make it select any element you click in the simulation. Plus, it would be really usefull. Especially with al the new elements, an easier way to select them would be great.
Andrewrox If your mouse has a Scroll Wheel, it can click when pressed downward, this would be the middle click he is referring to, but oddly enough I don't use many of the hot keys like SPACE for pausing.
i like it..its vary helpful even tho i just started to use indeed for some people it dousnt help cus they dont have a scrool wheels so BTW its only for the fun people