WPinternals/RootAccessTestUWP/MainPage.xaml

<Page
    x:Class="RootAccessTestUWP.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:RootAccessTestUWP"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
        <TextBlock x:Name="TextBlock"
                   Margin="10"
                   HorizontalAlignment="Stretch"
                   TextWrapping="Wrap"
                   Text=""
                   VerticalAlignment="Stretch"
                   FontFamily="Courier New" />
    </Grid>
</Page>