Apply an anchor offset for Anchor.TopRight too.

TestGame/TestGame.cs

@@ -142,7 +142,7 @@ public class TestGame : Game
     private HorizontalContainer _container = new(new Rect(128.0f, 64.0f), new(), 16)
     {
         ConfineToContents = true,
-        Anchor = Anchor.TopCenter,
-        AnchorOffset = new Vector2(0.5f, 0.0f)
+        Anchor = Anchor.TopRight,
+        AnchorOffset = new Vector2(1.0f, 0.0f)
     };
 }