Why a relative path doesn't work in my Seam code to redirect to a page in Gatein portal environment?

Issue

File download (i.e. exporting datatable results to Excel/PDF) is a critical requirement for us with the portal.  Just about every portlet we are using in the current 4.x version of the portal provides this functionality.  We are beginning to work on porting to Gate-In 3.0 and I cannot get the file download function to work.  Our datatable bean needs to perform a redirect to a FileDownloadServlet.  The portletbridge reference indicates we should be able to do this by using:

<h:commandLink actionListener="#{yourBean.yourListenr}">
 <f:param name="javax.portlet.faces.DirectLink" value="true"/>
</h:commandLink>

But I can't seem to redirect out of the portal.