     }
 }
 
+// MARK: Layout guide.
+
+extension UIViewController {
+    public var keyboardAlignmentLayoutGuide: UILayoutSupport? { return tabNavigationController?.keyboardAlignmentLayoutGuide }
+}
+
 extension ViewController {
     override func removeFromParentViewController() {
         super.removeFromParentViewController()

}

extension TabNavigationController {
    // MARK: - Public.
    // MARK: Tab view controllers.
    

        set { tabNavigationTitleActionItems = newValue }
    }
    
    lazy private var _tabNavigationBar: TabNavigationBar = _createGeneralTabNavigationBar()
    
    public override var keyboardAlignmentLayoutGuide: UILayoutSupport { return _keyboardAlignmentView }
    lazy fileprivate var _keyboardAlignmentView: _TabNavigationKeyboardAlignmentLayoutView = _createGeneralAlignmentView()
    fileprivate var _keyboardAlignmentViewHeightConstraint: NSLayoutConstraint!
    
    public var interactivePopGestureRecognizer: UIPanGestureRecognizer { return _panGestureRecognizer }
    fileprivate var _panGestureRecognizer: UIPanGestureRecognizer!
