code: public TabShowingAction show(final Tab tabToShow, final LmlTabbedPaneListener listener) {
          this.tabToShow = tabToShow;
          this.listener = listener;
          shown = false;
          return this;
      }
docs: Chaining action for pooling utility.
  
  @param tabToShow will be shown.
  @param listener manages tabs.
  @return this for chaining.