     open var backPosition: ButtonPosition = .right
     private var handlerView: UIView!
     
+    // true to pop back to a selected viewController
+    open var shouldNavigateToPreviousViewController: Bool = false
+    
     private var backButton: UIBarButtonItem!
     private var menuButton: UIBarButtonItem!
     

            for queueViewController in internalNavigationController.viewControllers
                where object_getClassName(queueViewController) == object_getClassName(viewController)
            {
                return
            }
            

            case .left:
                menuButton.customView!.alpha = 1
                navigationItem.leftBarButtonItem = menuButton
                menuView.isHidden = false
                break
            case .right:
                removeBackButton()
