tdlib-fork/example/uwp/app/App.xaml

<Application
    x:Class="TdApp.App"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:TdApp"
    RequestedTheme="Light">
</Application>