On the (on Mac) Cmd+(hold arrow) to rotate through the open windows is pretty cool, but when you tap the arrow key (instead of holding it), it just goes back and forth between two windows, which I can't see a use for. It seems it would be more useful to have the behavior to be: if you hold down the Cmd key and repeatedly tap the arrow hit, the windows rotate one after the other until you get through them all and recycle and v.v. for the opposite direction arrow.
Issue 2289:
http://code.google.com/p/pharo/issues/detail?id=2289
Cheers,
Sean