vue-java-tutorials/CSharp/WPFTutorial/WPF-4-Custom-User-Controls/App.xaml

<Application x:Class="WPF_4_Custom_User_Controls.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="clr-namespace:WPF_4_Custom_User_Controls"
             StartupUri="MainWindow.xaml">
    <Application.Resources>
         
    </Application.Resources>
</Application>