Best Practice for Sharing Styles in a Silverlight Application that uses the Prism Framework

A typ开发者_如何学Goical Silverlight Application that uses the Prism Framework consists of Modules and a Shell project. Each module can have it's own App.xaml. My question is what is the best practice for sharing styles? Should they be contained in the Shell App.xaml or in a common Assembly?

The best way I found was to store all resources aka styles in Styles.xaml and then reference it in your app.xaml as a resource dictionary. Then add a design time reference in each module doing so using blend 4.