Windows 8 Metro 应用开发App Bar问题

<Page.BottomAppBar>
<AppBar>
<AppBar.Resources>
<Style x:Key="MyAppBarButtonStyle" TargetType="Button" BasedOn="{StaticResource AppBarButtonStyle}">
<Setter Property="AutomationProperties.AutomationId" Value="MyAppBarButton"/>
<Setter Property="AutomationProperties.Name" Value="My Button"/>
<Setter Property="Content" Value="❁"/>
</Style>
</AppBar.Resources>
<StackPanel x:Name="LeftPanel" Orientation="Horizontal" Grid.Column="0" HorizontalAlignment="Left">
<Button x:Name="Edit" Style="{StaticResource MyAppBarButtonStyle}" Tag="MyButton"/>
</StackPanel>
</AppBar>
</Page.BottomAppBar>