public void RenderItem(int index, UIViewController viewController)
        {
            if (SelectedIndex != index)
            {
                SelectedIndex = index;
            }

            UINavigationController navController = ViewControllers[SelectedIndex] as UINavigationController;

            //UINavigationControllerExtensions.DisplayViewController(ViewControllers[SelectedIndex] as UINavigationController, viewController, true);
            navController.DisplayViewController(viewController, true);
        }
        public void PushToViewGroup(MXTouchViewGroup viewGroup, MXTouchViewGroupItem viewGroupItem, UIViewController viewController)
        {
            // let the group render itself if it needs to
            viewGroup.ViewController.Render(viewGroup);
            UIViewController viewGroupViewController = viewGroup.ViewController as UIViewController;

            // put the item in the proper view group
            int groupIndex = viewGroup.Items.FindIndex(vgi => vgi == viewGroupItem);

            viewGroup.ViewController.RenderItem(groupIndex, viewController);

            // only support the master for now
            if (_splitViewController == null && _masterNavigationController == null)
            {
                // first time through!
                Init(viewGroupViewController);
            }
            else
            {
                _masterNavigationController.DisplayViewController(viewGroupViewController, true);
            }
        }