Avalonia/samples/UnloadableAssemblyLoadContext/UnloadableAssemblyLoadContextPlug/TestControl.axaml

<Styles xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:controls="using:UnloadableAssemblyLoadContextPlug">
  <Design.PreviewWith>
    <controls:TestControl />
  </Design.PreviewWith>

  <Style Selector="controls|TestControl">
    <!-- Set Defaults -->
    <Setter Property="Template">
      <ControlTemplate>
        <TextBlock Text="Templated Control" />
      </ControlTemplate>
    </Setter>
  </Style>
</Styles>