Value indicating whether or not any active tweens were found
GreenSock Docs
TweenMax.isTweening()
TweenMax.isTweening( target:Object ) : Boolean
[static] Reports whether or not a particular object is actively tweening.
Parameters
target: Object
Target object whose tweens you’re checking
Returns : Boolean

Details
Reports whether or not a particular object is actively tweening. If a tween is paused, is completed, or hasn't started yet, it isn't considered active.