Fixed the build

src/Comet/Controls/NavigationView.cs

@@ -34,6 +34,8 @@ namespace Comet
 
 		protected Action<View> PerformNavigate { get; set; }
 
+		IToolbar INavigationView.Toolbar => null;
+
 		protected override void OnHandlerChange()
 		{
 			if (_views.Count == 0 && Content != null)

src/Comet/Controls/View.cs

@@ -782,7 +782,7 @@ namespace Comet
 
 		IShadow IView.Shadow => this.GetEnvironment<Graphics.Shadow>(EnvironmentKeys.View.Shadow);
 
-		//int IView.ZIndex => this.GetEnvironment<int?>(nameof(IView.ZIndex)) ?? 0;
+		int IView.ZIndex => this.GetEnvironment<int?>(nameof(IView.ZIndex)) ?? 0;
 
 		Size IView.Arrange(Rectangle bounds)
 		{