fixed Top issue

UICatalog/Scenarios/Keys.cs

@@ -51,7 +51,7 @@ namespace UICatalog.Scenarios {
 		public override void Init (Toplevel top, ColorScheme colorScheme)
 		{
 			Application.Init ();
-			Top = top;
+			Top = top != null ? top : Application.Top;
 
 			Win = new TestWindow ($"CTRL-Q to Close - Scenario: {GetName ()}") {
 				X = 0,

UICatalog/Scenarios/Notepad.cs

@@ -14,11 +14,7 @@ namespace UICatalog.Scenarios {
 		public override void Init (Toplevel top, ColorScheme colorScheme)
 		{
 			Application.Init ();
-
-			Top = top;
-			if (Top == null) {
-				Top = Application.Top;
-			}
+			Top = top != null ? top : Application.Top;
 			Top.ColorScheme = Colors.Base;
 		}