How to setup a slide to show if all other slides have been viewed?

As far as the how I track it - its really outside the scope here.  (I make an ajax call to php, grab a session variable that was set before they accessed the course, write some data in the database using some fields they filled in from the course, email a record of completion to them and their supervisor)  I understand that part is not supported which is fine.

What I have done in the past in presenter, is using flash, I can access the player object, and grab all the slides and their status (viewed or not).  And i can present things based on those results.

I have to assume I can do the same thing in storyline.  I say this because a status of each slide is being set somewhere as evident in the menu item turning a different color after a slide is viewed, as well as if I close it and open it again, and select yes I want to start where I left off.  Those menu items I have viewed are a different color.

Honestly, Even is its not an officially supported feature, thats fine - it just seems that having to set 40 variables, then check all 40 of them is a little silly.