Hello jean michel,
Attached is a sample project showing you an approach to your issue. Review it and tell me if this is what you want.
On a side note, I'd like to inform you that we've just released an online tool that allows you to reduce the size of your Silverlight applications. For more information, please visit http://blogs.telerik.com/blogs/posts/10-06-10/telerik_assembly_minifier.aspx
the Telerik team
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