Disable Next button until .swf is completed by the user

My customer is using Studio 13 and would like learners to be forced to click on each item in a .swf before moving to the next slide. I know how to disable the Next button for the entire slide and how to use timings, but this depends on user interaction rather than timings.

But how can I disable the Next button while the learner clicks each item in the .swf, and then enable the Next button when they click the final item in the .swf?

We are creating a custom Player so we would be able to incorporate any variables and programming if that would help.