code: @Override
      public Component newSubtree(final String _wicketId,
                                  final IModel<UIStructurBrowser> _model)
      {
          return new SubElement(_wicketId, this, _model);
      }
docs: Create a new subtree.
  
  @param _wicketId     wicket id for this component
  @param _model        the model of the new subtree
  @return the created component