Support for selected menu items

sky/sdk/example/stocks/lib/stock_home.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/editing/input.dart';
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/drawer.dart';
 import 'package:sky/widgets/drawer_header.dart';
 import 'package:sky/widgets/floating_action_button.dart';
 import 'package:sky/widgets/icon.dart';
@@ skipping 109 matching lines @@
   }
 
   Drawer buildDrawer() {
     return new Drawer(
       controller: _drawerController,
       level: 3,
       children: [
         new DrawerHeader(children: [new Text('Stocks')]),
         new MenuItem(
           icon: 'action/assessment',
+          selected: true,
           children: [new Text('Stock List')]),
         new MenuItem(
           icon: 'action/account_balance',
           children: [new Text('Account Balance')]),
         new MenuDivider(),
         new MenuItem(
           icon: 'action/thumb_up',
           onPressed: () => _handleStockModeChange(StockMode.optimistic),
           children: [
             new Flexible(child: new Text('Optimistic')),
@@ skipping 152 matching lines @@
         body: buildTabNavigator(),
         snackBar: buildSnackBar(),
         floatingActionButton: buildFloatingActionButton(),
         drawer: _drawerShowing ? buildDrawer() : null
       ),
     ];
     addMenuToOverlays(overlays);
     return new Stack(overlays);
   }
 }