code: public final boolean isScrollable(@NonNull final Area area) {
          return topScrollableArea != null && topScrollableArea.getIndex() <= area.getIndex() &&
                  bottomScrollableArea.getIndex() >= area.getIndex();
      }
docs: Returns, whether a specific area is scrollable.
  
  @param area
  The area, which should be checked, as a value of the enum {@link Area}. The area may
  not be null
  @return True, if the given area is scrollable, false otherwise