code: public void enableTab(E tabContent) {
  
          Integer index = new Integer(m_tabPanel.getWidgetIndex(tabContent));
          Element tab = getTabElement(index.intValue());
          if ((tab != null) && m_disabledTabIndexes.containsKey(index)) {
              tab.removeClassName(I_CmsLayoutBundle.INSTANCE.tabbedPanelCss().tabDisabled());
              tab.setTitle(m_disabledTabIndexes.get(index));
              m_disabledTabIndexes.remove(index);
          }
      }
docs: Enables the tab with the given index.<p>
  
  @param tabContent the content of the tab that should be enabled