anchor.diff:      );
     }
   }
  +
  +class _IconsDemoCard extends StatelessWidget {
  +
  +  const _IconsDemoCard(this.handleIconButtonPress);
  +
  +  final VoidCallback handleIconButtonPress;
  +
  +  Widget _buildIconButton(double iconSize, IconData icon, bool enabled) {
  +    return new IconButton(
  +      icon: new Icon(icon),
  +      iconSize: iconSize,
  +      tooltip: "${enabled ? 'Enabled' : 'Disabled'} icon button",
  +      onPressed: enabled ? handleIconButtonPress : null
  +    );
  +  }
  +
  +  Widget _centeredText(String label) =>
  +    new Padding(
  +      // Match the default padding of IconButton.
  +      padding: const EdgeInsets.all(8.0),
  +      child: new Text(label, textAlign: TextAlign.center),
  +    );
  +
  +  TableRow _buildIconRow(double size) {
  +    return new TableRow(
  +      children: <Widget> [
  +        _centeredText(size.floor().toString()),
  +        _buildIconButton(size, Icons.face, true),
  +        _buildIconButton(size, Icons.face, false),
  +      ],
  +    );
  +  }
  +
  +  @override
  +  Widget build(BuildContext context) {
  +    final ThemeData theme = Theme.of(context);
  +    final TextStyle textStyle = theme.textTheme.subhead.copyWith(color: theme.textTheme.caption.color);
  +    return new Card(
  +      child: new DefaultTextStyle(
  +        style: textStyle,
  +        child: new Table(
  +          defaultVerticalAlignment: TableCellVerticalAlignment.middle,
  +          children: <TableRow> [
  +            new TableRow(
  +              children: <Widget> [
  +                _centeredText('Size'),
  +                _centeredText('Enabled'),
  +                _centeredText('Disabled'),
  +              ]
  +            ),
  +            _buildIconRow(18.0),
  +            _buildIconRow(24.0),
  +            _buildIconRow(36.0),
  +            _buildIconRow(48.0),
  +          ],
  +        ),
  +      ),
  +    );
  +  }
  +}
  
positive.code:     });
    }
  
    Widget buildIconButton(double iconSize, IconData icon, bool enabled) {
      return new IconButton(
        icon: new Icon(icon),
        iconSize: iconSize,
        tooltip: "${enabled ? 'Enabled' : 'Disabled'} icon button",
        onPressed: enabled ? handleIconButtonPress : null
      );
    }
  
    Widget buildSizeLabel(int size, TextStyle style) {
      return new SizedBox(
        height: size.toDouble() + 16.0, // to match an IconButton's padded height
        child: new Center(
          child: new Text('$size', style: style)
        )
      );
    }
  
    @override
    Widget build(BuildContext context) {
      final ThemeData theme = Theme.of(context);
      final TextStyle textStyle = theme.textTheme.subhead.copyWith(color: theme.textTheme.caption.color);
  
      return new Scaffold(
        appBar: new AppBar(
          title: const Text('Icons')
  
negative.code:           padding: const EdgeInsets.all(24.0),
            child: new Column(
              children: <Widget>[
                new _IconsDemoCard(handleIconButtonPress),
              ],
            ),
          ),
  