How to switch to Light theme for Windows8 apps

<Application x:Class="win8mail.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="using:win8mail"
             xmlns:localData="using:win8mail.Data"
             RequestedTheme="Light">

    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>

                <!-- 
                    Styles that define common aspects of the platform look and feel
                    Required by Visual Studio project and item templates
                 -->
                <ResourceDictionary Source="Common/StandardStyles.xaml"/>
            </ResourceDictionary.MergedDictionaries>

            <!-- Application-specific resources -->

            <x:String x:Key="AppName">win8mail</x:String>
        </ResourceDictionary>
    </Application.Resources>
</Application>