     }
     
     private func _setupKeyboardAlignmentView() {
-        view.insertSubview(_keyboardAlignmentView, belowSubview: _contentScrollView)
-        _keyboardAlignmentView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
-        _keyboardAlignmentView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
-        _keyboardAlignmentView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
+        // view.insertSubview(_keyboardAlignmentView, belowSubview: _contentScrollView)
+        // _keyboardAlignmentView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
+        // _keyboardAlignmentView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
+        // _keyboardAlignmentView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
     }
     
     private func _transitionTabNavigationBarWithPercent(_ perecent: CGFloat, transition views: TabNavigationBar.TabNavigationTransitionContext?) {

        _setSelectedViewController(at: index, updateNavigationBar: true, updateNavigationItems: !isTabNavigationItemsUpdatingDisabledInRootViewControllers, animated: animated)
    }
    
    public func addViewController<T>(_ viewController: T) where T: UIViewController, T: TabNavigationReadable {
        if isViewLoaded {
            // Add view controller as child view controller if view of tab-navigation controller loaded.
            _addViewControllerWithoutUpdatingNavigationTitle(viewController)

    
    lazy private var _tabNavigationBar: TabNavigationBar = _createGeneralTabNavigationBar()
    
    // #if swift(>=4.0)
    // #else
    // public override var keyboardAlignmentLayoutGuide: UILayoutSupport { return _keyboardAlignmentView }
    // #endif
    // lazy fileprivate var _keyboardAlignmentView: _TabNavigationKeyboardAlignmentLayoutView = _createGeneralAlignmentView()
    // fileprivate var _keyboardAlignmentViewHeightConstraint: NSLayoutConstraint!
    
    public var interactivePopGestureRecognizer: UIPanGestureRecognizer { return _panGestureRecognizer }
    fileprivate var _panGestureRecognizer: UIPanGestureRecognizer!
