It need not be a FacesMessage - I just need a vehicle/semaphore/Event/Exception of some sort that can be passed from the about-to-be-expired session to the new session created when the login page loads, so that the login page knows whether or not to display a
your session has timed outmessage.
Here is some stuff I have read and tried:
https://jira.jboss.org/jira/browse/JBSEAM-2257 (the patch, namely)
You can try using Seam contextual event:
and Seam @Observer, to listen whenever the session has timeout to throw the message: