Start an AddressBook example (to test text fields)

sky/sdk/lib/theme/theme_data.dart

Index: sky/sdk/lib/theme/theme_data.dart
diff --git a/sky/sdk/lib/theme/theme_data.dart b/sky/sdk/lib/theme/theme_data.dart
index 0043ee132bb4b6c3354325f54f1daec5424ddf9a..e9be1bb2fe3288a3913d57bcf3813972dba1bede 100644
--- a/sky/sdk/lib/theme/theme_data.dart
+++ b/sky/sdk/lib/theme/theme_data.dart
@@ -23,6 +23,9 @@ class ThemeData {
       canvasColor = brightness == ThemeBrightness.dark ? colors.Grey[850] : colors.Grey[50],
       cardColor = brightness == ThemeBrightness.dark ? colors.Grey[800] : colors.White,
       dividerColor = brightness == ThemeBrightness.dark ? const Color(0x1FFFFFFF) : const Color(0x1F000000),
+      // Some users want the pre-multiplied color, others just want the opacity.
+      hintColor = brightness == ThemeBrightness.dark ? const Color(0x42FFFFFF) : const Color(0x4C000000),
+      hintOpacity = brightness == ThemeBrightness.dark ? 0.26 : 0.30,
       text = brightness == ThemeBrightness.dark ? typography.white : typography.black {
     assert(brightness != null);
 
@@ -52,6 +55,8 @@ class ThemeData {
   final Color canvasColor;
   final Color cardColor;
   final Color dividerColor;
+  final Color hintColor;
+  final double hintOpacity;
   final typography.TextTheme text;
 
   Color _primaryColor;