code: public void addItem(T value, Direction dir, String text) {
          addItem(value, dir, text, true);
      }
docs: Adds an item to the list box, specifying its direction and an initial
  value for the item.
  
  @param value the item's value, to be submitted if it is part of a
  {@link FormPanel}; cannot be <code>null</code>
  @param dir   the item's direction
  @param text  the text of the item to be added