public void allocate_preferred_size (AllocationFlags flags)
Allocates the natural size of this.
This function is a utility call for Actor implementations that allocates the actor's preferred natural size. It can be used by fixed layout managers (like Group or so called 'composite actors') inside the ClutterActor::allocate implementation to give each child exactly how much space it requires, regardless of the size of the parent.
This function is not meant to be used by applications. It is also not meant to be used outside the implementation of the allocate virtual function.
flags controlling the allocation