In some versions of the Dev Express XAF Framework exists a problem of the visual studio 2010 designer which should open *.xafml files. If you open such files you will be able to see the following error: "One or more errors encountered while loading the designer. The errors are listed below. Some errors can be fixed may require code or model changes. Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information. "Read More
The good article about customization the AD FS login flow in OWA.