DTTG + DT4 are turning into a great combination - just begging Devs for the option for a distraction free reading environment in DTTG (pdfs etc) - especially retaining option to highlight/mark-up docs.
Please devs, lemmie slide that ol’ top-bar out of the way & focus on the markup 
The request is noted, with no promises.
I think you have it, except the annoying toolbar. You can “remove” the side bar both in portrait and landscape view and then you have a full screen. I use that to read PDF-books. If you select horizontal scrolling in page mode, a touch in the border of the PDF advances one page like in an eBook. Even in landscape you can have two-page view of a PDF that acts like an eBook.
Thanks & yup, it’s the toolbar at the top I’m talking about - sliding it up (or if not possible a sparse/reduced version) would be great to immerse in docs for longform reading/annotation