Make the drawer, popup menus, dialogs, and settings page scrollable.

sky/sdk/lib/widgets/dialog.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 '../theme/colors.dart' as colors;
 import 'basic.dart';
 import 'default_text_style.dart';
 import 'material.dart';
-import "theme.dart";
+import 'scrollable_viewport.dart';
+import 'theme.dart';
 
 /// A material design dialog
 ///
 /// <https://www.google.com/design/spec/components/dialogs.html>
 class Dialog extends Component {
   Dialog({
     String key,
     this.title,
     this.content,
     this.actions,
@@ skipping 61 matching lines @@
       ),
       new Center(
         child: new Container(
           margin: new EdgeDims.symmetric(horizontal: 40.0, vertical: 24.0),
           child: new ConstrainedBox(
             constraints: new BoxConstraints(minWidth: 280.0),
             child: new Material(
               level: 4,
               color: _color,
               child: new ShrinkWrapWidth(
-                child: new Block(children)
+                child: new ScrollableBlock(children)
               )
             )
           )
         )
       )
     ]);
   }
 }