Support for selected menu items

sky/sdk/lib/widgets/menu_item.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 '../painting/text_style.dart';
 import 'basic.dart';
 import 'button_base.dart';
 import 'default_text_style.dart';
 import 'icon.dart';
 import 'ink_well.dart';
 import 'theme.dart';
 import 'widget.dart';
 
 const BoxDecoration _kHighlightDecoration = const BoxDecoration(
   backgroundColor: const Color.fromARGB(102, 153, 153, 153)
 );
 
 // TODO(abarth): We shouldn't need _kHighlightBoring, but currently Container
 //               isn't smart enough to retain the components it builds when we
 //               add or remove a |decoration|. For now, we use a transparent
 //               decoration to avoid changing the structure of the tree. The
 //               right fix, however, is to make Container smarter about how it
 //               syncs its subcomponents.
 const BoxDecoration _kHighlightBoring = const BoxDecoration(
   backgroundColor: const Color.fromARGB(0, 0, 0, 0)
 );
 
 class MenuItem extends ButtonBase {
-  MenuItem({ String key, this.icon, this.children, this.onPressed })
+  MenuItem({ String key, this.icon, this.children, this.onPressed, this.selected: false })
     : super(key: key);
 
   String icon;
   List<Widget> children;
   Function onPressed;
+  bool selected;
 
   void syncFields(MenuItem source) {
     icon = source.icon;
     children = source.children;
     onPressed = source.onPressed;
+    selected = source.selected;
     super.syncFields(source);
   }
 
   TextStyle get textStyle {
     TextStyle result = Theme.of(this).text.body2;
     if (highlight)
       result = result.copyWith(color: Theme.of(this).primaryColor);
     return result;
   }
 
   String get iconSuffix {
     switch(Theme.of(this).brightness) {
       case ThemeBrightness.dark:
         return "white";
       case ThemeBrightness.light:
         return "black";
     }
   }
 
   Widget buildContent() {
     List<Widget> flexChildren = new List<Widget>();
     if (icon != null) {
       flexChildren.add(
         new Opacity(
-          opacity: highlight ? 1.0 : 0.45,
+          opacity: selected ? 1.0 : 0.45,
           child: new Padding(
             padding: const EdgeDims.symmetric(horizontal: 16.0),
             child: new Icon(type: "${icon}_${iconSuffix}", size: 24)
           )
         )
       );
     }
     flexChildren.add(
       new Flexible(
         child: new Padding(
           padding: const EdgeDims.symmetric(horizontal: 16.0),
           child: new DefaultTextStyle(
             style: textStyle,
             child: new Flex(children, direction: FlexDirection.horizontal)
           )
         )
       )
     );
     return new Listener(
       onGestureTap: (_) {
         if (onPressed != null)
           onPressed();
       },
       child: new Container(
         height: 48.0,
-        decoration: highlight ? _kHighlightDecoration : _kHighlightBoring,
-        child: new InkWell(
-          child: new Flex(flexChildren)
+        decoration: selected ? _kHighlightDecoration : _kHighlightBoring,
+        child: new Container(
+          decoration: highlight ? _kHighlightDecoration : _kHighlightBoring,
+          child: new InkWell(
+            child: new Flex(flexChildren)
+          )
         )
       )
     );
   }
 }