Using the webview wrapper control to display content from a URL with fallback local content

WebViewHostSample.xaml

<Page
    x:Class="Metro.Controls.Demo.Samples.WebViewHostSample"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:MetroControls="using:MetroControls"
    mc:Ignorable="d"
    d:DesignHeight="300"
    d:DesignWidth="400">
    
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition />
        </Grid.RowDefinitions>
        
        <MetroControls:WebViewHostControl HeaderText="Help content that should work" 
                                          Uri="http://www.bing.com"
                                          LocalFallbackUri="/Assets/LocalHelp.html" />

        <MetroControls:WebViewHostControl Grid.Row="1"
                                          HeaderText="Help content with fallback for failed navigation" 
                                          Uri="http://somethinginvalidhere.fail"
                                          LocalFallbackUri="/Assets/LocalHelp.html" />

    </Grid>
</Page>