I know the what questions are on topic, but I fail to understand, why asking about pdf-viewing has fallen out? I did not ask about shopping recommendation.
I express disappointment that 5 people did close my question, and no one cared to explain why.
By this logic one should close every question, once it gets a single accepted answer
is a gross oversimplification of what I said. I was just pointing out the relatively obscurity of this feature (at least relative to the desktop market, as if that wasn't the case you'd have no reason to ask this in the first place), and that it's unlikely you'll find any answers outside of modifying a PDF viewer or the PDF's themselves. Search as I might, I can only find references to this "feature" in Android software - thus my comments...