Return the list of presentations (decorated). Also check to see if the user is allowed to update the content area so the proper buttons are made available.
Return a string indicating the current show position as an example: "1 of 5" the expectation is that there will be a message like Viewing: 1 of 5 Viewing: No current presentation
Position Insdicator String
Process the "Previous" action. This causes the current show to move the current slide to the previous slide. It will not go past the first slide.
the navigation outcome.