Xamarin.Forms-Samples/FormulaOneApp/FormulaOneApp.Classic.Windows/App.xaml

<Application
    x:Class="FormulaOneApp.Classic.Windows.App"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:converters="using:FormulaOneApp.Classic.Windows.Converters">
    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="/Themes/Colors.xaml"  />
                <ResourceDictionary Source="/Themes/Hub.xaml"/>
                <ResourceDictionary Source="/Themes/List.xaml"/>
            </ResourceDictionary.MergedDictionaries>
            
            <!-- Converters -->
            <converters:NativeEventToImageConverter x:Key="EventToImageConverter" />
        </ResourceDictionary>
    </Application.Resources>
</Application>