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>

　　http://social.msdn.microsoft.com/Forums/zh-CN/metroappzhcn/thread/e2a23a8f-9e29-46f7-bc3a-a28558f46a6d/