Avalonia/samples/VirtualizationDemo/App.axaml

<Application xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             x:Class="VirtualizationDemo.App">
  <Application.Styles>
    <FluentTheme/>
  </Application.Styles>
  <Application.Resources>
    <ResourceDictionary>
      <ResourceDictionary.MergedDictionaries>
        <ResourceInclude Source="avares://ControlSamples/HamburgerMenu/HamburgerMenu.xaml" />
      </ResourceDictionary.MergedDictionaries>
    </ResourceDictionary>
  </Application.Resources>
</Application>