Simplify Scaffold

Rather than using a custom render object, we can just use a Stack.

examples/address_book/lib/main.dart

@@ -81,7 +81,7 @@ class AddressBookHome extends StatelessComponent {
 
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: buildToolBar(context),
+      toolBar: buildToolBar(context),
       body: buildBody(context),
       floatingActionButton: buildFloatingActionButton(context)
     );

examples/demo_launcher/lib/main.dart

@@ -192,7 +192,7 @@ final ThemeData _theme = new ThemeData(
 class DemoHome extends StatelessComponent {
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: new ToolBar(center: new Text('Sky Demos')),
+      toolBar: new ToolBar(center: new Text('Sky Demos')),
       body: new Material(
         type: MaterialType.canvas,
         child: new DemoList()

examples/fitness/lib/feed.dart

@@ -219,7 +219,7 @@ class FeedFragmentState extends State<FeedFragment> {
 
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: buildToolBar(),
+      toolBar: buildToolBar(),
       body: buildBody(),
       snackBar: new Placeholder(key: _snackBarPlaceholderKey),
       floatingActionButton: buildFloatingActionButton()

examples/fitness/lib/meal.dart

@@ -105,7 +105,7 @@ class MealFragmentState extends State<MealFragment> {
 
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: buildToolBar(),
+      toolBar: buildToolBar(),
       body: buildBody()
     );
   }

examples/fitness/lib/measurement.dart

@@ -200,7 +200,7 @@ class MeasurementFragmentState extends State<MeasurementFragment> {
 
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: buildToolBar(),
+      toolBar: buildToolBar(),
       body: buildBody(context),
       snackBar: new Placeholder(key: _snackBarPlaceholderKey)
     );

examples/fitness/lib/settings.dart

@@ -122,7 +122,7 @@ class SettingsFragmentState extends State<SettingsFragment> {
 
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: buildToolBar(),
+      toolBar: buildToolBar(),
       body: buildSettingsPane(context)
     );
   }

examples/mine_digger/lib/main.dart

@@ -182,7 +182,7 @@ class MineDiggerState extends State<MineDigger> {
     return new Title(
       title: 'Mine Digger',
       child: new Scaffold(
-        toolbar: buildToolBar(context),
+        toolBar: buildToolBar(context),
         body: new Container(
           child: new Center(child: board),
           decoration: new BoxDecoration(backgroundColor: Colors.grey[50])

examples/stocks/lib/stock_home.dart

@@ -237,7 +237,7 @@ class StockHomeState extends State<StockHome> {
 
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: _isSearching ? buildSearchBar() : buildToolBar(),
+      toolBar: _isSearching ? buildSearchBar() : buildToolBar(),
       body: buildTabNavigator(),
       snackBar: new Placeholder(key: _snackBarPlaceholderKey),
       floatingActionButton: buildFloatingActionButton()

examples/stocks/lib/stock_settings.dart

@@ -119,7 +119,7 @@ class StockSettingsState extends State<StockSettings> {
 
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: buildToolBar(context),
+      toolBar: buildToolBar(context),
       body: buildSettingsPane(context)
     );
   }

examples/stocks/lib/stock_symbol_viewer.dart

@@ -25,7 +25,7 @@ class StockSymbolViewerState extends State<StockSymbolViewer> {
     TextStyle headings = Theme.of(context).text.body2;
 
     return new Scaffold(
-      toolbar: new ToolBar(
+      toolBar: new ToolBar(
         left: new IconButton(
           icon: 'navigation/arrow_back',
           onPressed: config.navigator.pop

examples/widgets/card_collection.dart

@@ -342,7 +342,7 @@ class CardCollectionState extends State<CardCollection> {
     }
 
     return new Scaffold(
-      toolbar: buildToolBar(),
+      toolBar: buildToolBar(),
       body: body
     );
   }

examples/widgets/date_picker.dart

@@ -34,7 +34,7 @@ class DatePickerDemoState extends State<DatePickerDemo> {
       ),
       child: new Stack([
         new Scaffold(
-          toolbar: new ToolBar(center: new Text("Date Picker")),
+          toolBar: new ToolBar(center: new Text("Date Picker")),
           body: new Material(
             child: new Row(
               [new Text(_dateTime.toString())],

examples/widgets/drag_and_drop.dart

@@ -101,7 +101,7 @@ class DragAndDropApp extends StatefulComponent {
 class DragAndDropAppState extends State<DragAndDropApp> {
   Widget build(BuildContext context) {
     return new Scaffold(
-      toolbar: new ToolBar(
+      toolBar: new ToolBar(
         center: new Text('Drag and Drop Flutter Demo')
       ),
       body: new Material(

examples/widgets/ensure_visible.dart

@@ -89,7 +89,7 @@ class EnsureVisibleApp extends App {
         child: new Title(
           title: 'Cards',
           child: new Scaffold(
-            toolbar: new ToolBar(center: new Text('Tap a Card')),
+            toolBar: new ToolBar(center: new Text('Tap a Card')),
             body: cardCollection
           )
         )

examples/widgets/overlay_geometry.dart

@@ -138,7 +138,7 @@ class OverlayGeometryAppState extends State<OverlayGeometryApp> {
   Widget build(BuildContext context) {
     List<Widget> layers = <Widget>[
       new Scaffold(
-        toolbar: new ToolBar(center: new Text('Tap a Card')),
+        toolBar: new ToolBar(center: new Text('Tap a Card')),
         body: new Container(
           padding: const EdgeDims.symmetric(vertical: 12.0, horizontal: 8.0),
           decoration: new BoxDecoration(backgroundColor: Theme.of(context).primarySwatch[50]),

examples/widgets/pageable_list.dart

@@ -149,7 +149,7 @@ class PageableListAppState extends State<PageableListApp> {
     return new IconTheme(
       data: const IconThemeData(color: IconThemeColor.white),
       child: new Scaffold(
-        toolbar: buildToolBar(),
+        toolBar: buildToolBar(),
         body: buildBody(context)
       )
     );

examples/widgets/progress_indicator.dart

@@ -103,7 +103,7 @@ class ProgressIndicatorAppState extends State<ProgressIndicatorApp> {
         child: new Title(
           title: 'Progress Indicators',
           child: new Scaffold(
-            toolbar: new ToolBar(center: new Text('Progress Indicators')),
+            toolBar: new ToolBar(center: new Text('Progress Indicators')),
             body: new DefaultTextStyle(
               style: Theme.of(context).text.title,
               child: body

examples/widgets/scale.dart

@@ -59,7 +59,7 @@ class ScaleAppState extends State<ScaleApp> {
     return new Theme(
       data: new ThemeData.dark(),
       child: new Scaffold(
-        toolbar: new ToolBar(
+        toolBar: new ToolBar(
             center: new Text('Scale Demo')),
         body: new Material(
           type: MaterialType.canvas,

examples/widgets/sector.dart

@@ -124,7 +124,7 @@ class SectorApp extends App {
       child: new Title(
         title: 'Sector Layout',
         child: new Scaffold(
-          toolbar: new ToolBar(
+          toolBar: new ToolBar(
             center: new Text('Sector Layout in a Widget Tree')
           ),
           body: buildBody()

examples/widgets/styled_text.dart

@@ -106,7 +106,7 @@ HAL: This mission is too important for me to allow you to jeopardize it.''';
           color: Colors.grey[50],
           child: interactiveBody
         ),
-        toolbar: new ToolBar(
+        toolBar: new ToolBar(
           center: new Text('Hal and Dave')
         )
       )

examples/widgets/tabs.dart

@@ -131,7 +131,7 @@ class TabbedNavigatorAppState extends State<TabbedNavigatorApp> {
     );
 
     return new Scaffold(
-      toolbar: toolbar,
+      toolBar: toolbar,
       body: tabNavigator
     );
   }

packages/flutter/lib/src/material/constants.dart

@@ -14,6 +14,7 @@ const double kStatusBarHeight = 50.0;
 // Mobile Portrait: 56dp
 // Tablet/Desktop: 64dp
 const double kToolBarHeight = 56.0;
+const double kSnackBarHeight = 52.0;
 
 const double kMaterialDrawerHeight = 140.0;
 const double kScrollbarSize = 10.0;

packages/flutter/lib/src/widgets/snack_bar.dart

@@ -15,7 +15,6 @@ import 'package:sky/src/widgets/placeholder.dart';
 import 'package:sky/src/widgets/theme.dart';
 import 'package:sky/src/widgets/transitions.dart';
 
-const double _kSnackHeight = 52.0;
 const double _kSideMargins = 24.0;
 const double _kVerticalPadding = 14.0;
 const Color _kSnackBackground = const Color(0xFF323232);
@@ -72,14 +71,14 @@ class SnackBar extends StatelessComponent {
       performance: performance,
       height: new AnimatedValue<double>(
         0.0,
-        end: _kSnackHeight,
+        end: kSnackBarHeight,
         curve: easeIn,
         reverseCurve: easeOut
       ),
       child: new ClipRect(
         child: new OverflowBox(
-          minHeight: _kSnackHeight,
-          maxHeight: _kSnackHeight,
+          minHeight: kSnackBarHeight,
+          maxHeight: kSnackBarHeight,
           child: new Material(
             level: 2,
             color: _kSnackBackground,