Fix all the components to pick the right colours from the theme.

sky/sdk/example/stocks/lib/main.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/theme/colors.dart' as colors;
+import 'package:sky/theme/typography.dart' as typography;
 import 'package:sky/widgets/basic.dart';
+import 'package:sky/widgets/default_text_style.dart';
 import 'package:sky/widgets/navigator.dart';
 import 'package:sky/widgets/theme.dart';
 import 'package:sky/widgets/widget.dart';
 
 import 'stock_data.dart';
 import 'stock_home.dart';
 import 'stock_settings.dart';
 import 'stock_types.dart';
 
 class StocksApp extends App {
@@ skipping 56 matching lines @@
       );
     } else {
       theme = new ThemeData.dark(
         primary: colors.Red,
         accent: colors.PurpleAccent
       );
     }
 
     return new Theme(
       data: theme,
-        child: new Navigator(_navigationState)
+        child: new DefaultTextStyle(
+          style: typography.error, // if you see this, you've forgotten to correctly configure the text style!
+          child: new Navigator(_navigationState)
+        )
      );
    }
 }
 
 void main() {
   runApp(new StocksApp());
 }