If someone looks into NSAnimation, it is worth reviewing its memory
management.
I tried to use NSAnimation some time ago, and gave up because it was
leaking memory.
I did a quick look at it at the time, and there is a retain cycle
between NSAnimation and
GSAnimator. When I broke this (by removing the retaining of
NSAnimation in GSAnimator),
I just went a bit further until another retain cycle, and I gave up as
I did not have enough time,
and changed my code to not use it. My intention was to come back and
try harder to find
this or at least file a bug report, but I did neither...