public interface ICachedFillLayout
This layouter renders the first visible child of the container into the whole available space and caches the size
of its children, so the next time the layout will be done, the cached values will be used until
the cache is cleared by the user.
In many cases, the min, max and pref size of the child container will not change until the child container
has not been changed by adding or removing children. So using this layout manager as a parent for a complicate
layout can improve performance extremely. The tradeoff is, that the programmer has to take care for container
changes itself and clearing the cache.