Currently, when I set an Authentication Timeout value in my access group like so:

...and ensure that "Use access group timeout" in the Platform Authentication service is ticked like this:

...I see this behaviour when I try to do something in the portal after the timeout:

Ideally I would like to be able to change this behaviour so that the user is presented with a screen with a message that says: "Your session has expired. Please click here to go back in."

Does anyone know if this is possible?

Please note that I know how to do this with a custom authentication service. That is NOT what I am looking for here. I am also not interested in using @baseclass.pxSessionTimer Section.