Xamarin.Forms-Samples/Xamarin.Forms Windows Preview/Xamarin.Forms_Windows.Windows/MainPage.xaml

<winRt:WindowsPage
    x:Class="Xamarin.Forms_Windows.Windows.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:Xamarin.Forms_Windows.Windows"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:winRt="using:Xamarin.Forms.Platform.WinRT"
    mc:Ignorable="d">
    <Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">

    </Grid>
</winRt:WindowsPage>