Looks like there are some problems with the algorithm. Not all marker stacks are rotated. If this check is removed and explicit `ovelapsVertically` is added below then all stack markers begin to rotate, but not consistently. If there are two stacks: 2 and 5 markers, then the 5 marker stack will rotate on every Space press, but the 2 marker stack won't rotate on each Space press (although it will eventually rotate).