code: public void add(Widget w, String tabText, boolean asHTML) {
          insert(w, tabText, asHTML, getWidgetCount());
      }
docs: Adds a widget to the tab panel. If the Widget is already attached to the
  TabPanel, it will be moved to the right-most index.
  
  @param w the widget to be added
  @param tabText the text to be shown on its tab
  @param asHTML <code>true</code> to treat the specified text as HTML