I first created a UserControl.
In the xaml I can reference StaticResources that are in the main Application's Resources.
I then refactored this UserControl to a Control and via Themes/Generic.xaml,
I apply a ControlTemplate (I needed this).
But this way the StaticResources are not found anymore (an XamlParseException is thrown at runtime).
I could merge the ResourceDictionaries that contain the StaticResource I need also in the Genericl.xaml file, but I'd like to avoid this due to performance issues
What are the mechanics behind this behaviour?