When viewing a document, I can enter a mode where I'm able to bookmark pages, jump to another bookmark, preview other pages in the document, or jump to any arbitrary page. This is quite useful. My problem is that I can never enter this mode intentionally, only accidentally, and I've never been able to figure out what I did to access this mode.

The default document "Getting Started With Documents" terms this the "overlay toolbar" and contains instructions on how to access it:

"You can store the relevant part of a document by
placing a bookmark. Bring up the overlay toolbar by
tapping or clicking anywhere on the document."

"You can quickly get to any point of the document by
bringing up the overlay scrub bar. Just tap or click
anywhere on the document to bring up the control."

But this doesn't work. Does this document need updated, or is the feature broken?