[Effen] Use the checkbox widget in the stocks app.

sky/framework/components/checkbox.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 '../fn.dart';
 import 'button_base.dart';
+import 'dart:sky' as sky;

[eseidel, 2015/05/12 21:34:42]

Do you want this?

 
 typedef void ValueChanged(value);
 
 class Checkbox extends ButtonBase {
   static final Style _style = new Style('''
     transform: translateX(0);
     display: flex;
     flex-direction: row;
     justify-content: center;
     align-items: center;
@@ skipping 60 matching lines @@
                 style: checked ? _checkedStyle : _uncheckedStyle
               )
             ]
           )
         ]
       ),
       onGestureTap: _handleClick
     );
   }
 }