             _panGestureBeginsTransform = (_formerViewController.view.transform, _topViewController.view.transform)
             _panGestureBeginsClips = _topViewController.view.clipsToBounds
             
-            _transitionNavigationBarViews = tabNavigationBar.beginTransitionNavigationTitleItems(_panGestureBeginsTitleItems, actionsConfig: { () -> (ignore: Bool, actions: [TabNavigationTitleActionItem]?) in
+            _transitionNavigationBarViews = tabNavigationBar.beginTransitionNavigationTitleItems(_panGestureBeginsTitleItems, selectedIndex: _viewControllersStack.startIndex == _viewControllersStack.index(before: _viewControllersStack.endIndex) ? _rootViewControllersInfo.selectedIndex : 0, actionsConfig: { () -> (ignore: Bool, actions: [TabNavigationTitleActionItem]?) in
                 return (false, actionsWhenPushed)
             }, navigationItems: _formerViewController.tabNavigationItems)
             _transitionNavigationBarViews?.titleViews.toItemViews.itemsView.alpha = 0.0

            _topViewController.view.transform = CGAffineTransform(translationX: transitionPercent * _topViewController.view.bounds.width, y: 0.0)
            _formerViewController.view.transform = CGAffineTransform(translationX: -(1.0-transitionPercent) * _formerViewController.view.bounds.width / 2.0, y: 0.0)
            _topViewController.view.clipsToBounds = false
            _setupTransitionShadowOfViewController(_topViewController)
            _topViewController.view.layer.shadowOpacity = Float(1.0-transitionPercent) * Float(0.5)
            
            _transitionTabNavigationBarWithPercent(transitionPercent, transition: _transitionNavigationBarViews)
        case .cancelled: fallthrough

    // MARK: - Actions.
    
    @objc
    private func _handlePanGestureRecognizer(_ sender: UIPanGestureRecognizer) {
        switch sender.state {
        case .possible: fallthrough
        case .began:
