Add an example of an app that manipulates both a RenderObject tree and has some fn logic in it.

sky/examples/stocks2/lib/stock_app.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import 'package:sky/framework/editing2/input.dart';
 import 'package:sky/framework/theme2/colors.dart' as colors;
 import 'package:sky/framework/widgets/drawer.dart';
 import 'package:sky/framework/widgets/drawer_header.dart';
 import 'package:sky/framework/widgets/floating_action_button.dart';
 import 'package:sky/framework/widgets/icon.dart';
 import 'package:sky/framework/widgets/icon_button.dart';
 import 'package:sky/framework/widgets/menu_divider.dart';
 import 'package:sky/framework/widgets/menu_item.dart';
 import 'package:sky/framework/widgets/modal_overlay.dart';
 import 'package:sky/framework/widgets/popup_menu.dart';
 import 'package:sky/framework/widgets/radio.dart';
 import 'package:sky/framework/widgets/scaffold.dart';
 import 'package:sky/framework/widgets/tool_bar.dart';
+import 'package:sky/framework/widgets/ui_node.dart';
 import 'package:sky/framework/widgets/wrappers.dart';
 
 import 'stock_data.dart';
 import 'stock_list.dart';
 import 'stock_menu.dart';
 
 enum StockMode { optimistic, pessimistic }
 
 class StocksApp extends App {
 
@@ skipping 177 matching lines @@
       ),
     ];
     addMenuToOverlays(overlays);
     return new Stack(overlays);
   }
 }
 
 void main() {
   print("starting stocks app!");
   App app = new StocksApp();
-  app.appView.onFrame = () {
+  UINodeAppView.appView.onFrame = () {
     // uncomment this for debugging:
     // app.appView.debugDumpRenderTree();
   };
 }