anchor.diff:    /// Typically these widgets are [IconButton]s representing common operations.
     /// For less common operations, consider using a [PopupMenuButton] as the
     /// last action.
  -  ///
  -  /// {@tool snippet --template=stateless_widget_material}
  -  ///
  -  /// This sample shows adding an action to an [AppBar] that opens a shopping cart.
  -  ///
  -  /// ```dart
  -  /// Widget build(BuildContext context) {
  -  ///   return Scaffold(
  -  ///     appBar: AppBar(
  -  ///       title: Text('Ready, Set, Shop!'),
  -  ///       actions: <Widget>[
  -  ///         IconButton(
  -  ///           icon: Icon(Icons.shopping_cart),
  -  ///           tooltip: 'Open shopping cart',
  -  ///           onPressed: () {
  -  ///             // Implement navigation to shopping cart page here...
  -  ///             print('Shopping cart opened.');
  -  ///           },
  -  ///         ),
  -  ///       ],
  -  ///     ),
  -  ///   );
  -  /// }
  -  /// ```
  -  /// {@end-tool}
     final List<Widget> actions;
   
     /// This widget is stacked behind the toolbar and the tab bar. It's height will
  
positive.code: import 'text_theme.dart';
  import 'theme.dart';
  
  // Examples can assume:
  // void _airDress() { }
  // void _restitchDress() { }
  // void _repairDress() { }
  
  const double _kLeadingWidth = kToolbarHeight; // So the leading button is square.
  
  // Bottom justify the kToolbarHeight child which may overflow the top.
  
negative.code: /// to false. In that case a null leading widget will result in the middle/title widget
  /// stretching to start.
  ///
  /// {@tool snippet --template=stateless_widget_material}
  ///
  /// This sample shows an [AppBar] with two simple actions. The first action
  /// opens a [SnackBar], while the second action navigates to a new page.
  ///
  /// ```dart preamble
  /// final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
  /// final SnackBar snackBar = const SnackBar(content: Text('Showing Snackbar'));
  ///
  /// void openPage(BuildContext context) {
  ///   Navigator.push(context, MaterialPageRoute(
  ///     builder: (BuildContext context) {
  ///       return Scaffold(
  ///         appBar: AppBar(
  ///           title: const Text('Next page'),
  ///         ),
  ///         body: const Center(
  ///           child: Text(
  ///             'This is the next page',
  ///             style: TextStyle(fontSize: 24),
  ///           ),
  ///         ),
  ///       );
  ///     },
  ///   ));
  /// }
  /// ```
  ///
  /// ```dart
  /// Widget build(BuildContext context) {
  ///   return Scaffold(
  ///     key: scaffoldKey,
  ///     appBar: AppBar(
  ///       title: const Text('AppBar Demo'),
  ///       actions: <Widget>[
  ///         IconButton(
  ///           icon: const Icon(Icons.add_alert),
  ///           tooltip: 'Show Snackbar',
  ///           onPressed: () {
  ///             scaffoldKey.currentState.showSnackBar(snackBar);
  ///           },
  ///         ),
  ///         IconButton(
  ///           icon: const Icon(Icons.navigate_next),
  ///           tooltip: 'Next page',
  ///           onPressed: () {
  ///             openPage(context);
  ///           },
  ///         ),
  ///       ],
  ///     ),
  ///     body: const Center(
  ///       child: Text(
  ///         'This is the home page',
  ///         style: TextStyle(fontSize: 24),
  ///       ),
  ///     ),
  ///   );
  /// }
  /// ```
  /// {@end-tool}
  ///
  