Page-by-page control of student navigation

This is Technique 28 in my book Lectora 301 - Interesting Courses Using Variables & More.

I copied and pasted the solution from my book. It looks fine in the Edit window but when it posts there is a lot of extra white space. Can't get it out. Sorry.

There are times when you want the learner to progress through a course from the beginning to the end but you still want to allow navigation anywhere in the pages already viewed using a Table of Contents. While there is no way to do this directly using the TOC, you can bounce the learner back if they try to jump ahead.

Warning: This could get real annoying if the learner has already viewed the course and is taking it as a review.

Here are the actions. The variable _largest has an initial value of zero and is a retained variable.

These actions return the learner back to the original page with no indication of what happened. If you want to let them know, then you can add this action before all the actions above. That way it uses the _pg_diff calculated on the jumped-to page, not the current page.