code: public Tabs setAjaxBeforeActivateEvent(ITabsAjaxEvent beforeActivateEvent)
  	{
  		this.ajaxEvents.put(TabEvent.beforeActivate, beforeActivateEvent);
  		setBeforeActivateEvent(new TabsAjaxBeforeActivateJsScopeUiEvent(this, TabEvent.beforeActivate, false));
  		return this;
  	}
docs: Sets the call-back for the AJAX beforeActivate event.
  
  @param beforeActivateEvent
  The ITabsAjaxEvent.