@Settable
 public void setDurationSecs(double seconds) {
   myFrameDuration = SecondsToFrames.getFramesForSeconds(seconds);
 }
 private void initialize(double spanSeconds, GameObjectQueue objects) {
   myFrameDuration = SecondsToFrames.getFramesForSeconds(spanSeconds);
   myFramesSinceStart = 0;
   generateReleaseTimes(objects);
 }