The IEffectTimer interface is the basic interface for the
class that updates effects like tweens. Different
IEffectTimer implementations are tuned for various
runtime environments like mobile, Flash, desktop,
or even automated testing where the currentTime is
controlled so the animation updates its target at
predictable positions on the screen.
Stop getting update events. Current time
should theoretically keep advancing, but events
are not dispatched so most implementations
stop the platform timer (which can save battery
on mobile devices) because they know that
when start() is called they have a way of
getting the updated current time.