A document's Contents lists every part again

On a document made of several parts — a course with lessons, say — the Contents index was showing only some of them. The rest were pushed off the list by material from inside the parts: quizzes, solutions, exercises and their source. What remained appeared in no useful order, and the list ran out before the missing parts were reached, so scrolling did not help either.

Contents now lists the parts of the document, in order, all of them. Nothing has become harder to reach: each entry still opens into its own contents, which is how you get to what is inside a part.