public virtual void allocate
Called by the parent of an actor to assign the actor its size.
Should never be called by applications (except when implementing a container or layout manager).
Actors can know from their allocation box whether they have moved with respect to their parent actor. The
describes additional information about the allocation, for instance whether the parent has moved with respect to the stage, for example because
a grandparent's origin has moved.
||new allocation of the actor, in parent-relative coordinates
||flags that control the allocation