This was actually surprisingly difficult for me to figure out since there is basically no discoverability hints anywhere, and I literally found it by accident.
In the Dropbox app for iPad, if you open a Word or other Office document, there is a little button in the lower right hand corner for viewing the document in full-screen. However, if you open a PDF document, that button is not present. Hmmm…
Additionally, in the iOS 5 version of the Dropbox app, there used to be an arrow button in the navigation bar area to toggle the visibility of the navigation panel on the left. This served as an adequate almost-full-screen view of a PDF, but the (as of March 10, 2014) current version of the Dropbox app removed that functionality.
So for months I was in a bit of a predicament regarding how to view a PDF in the app – double-tap zoomed, but didn’t remove the Panel from the split view controller. But just this weekend, immedately after sending an email to Dropbox lamenting the loss of the full-screen PDF feature, I discovered accidentally how to do it. It’s not immediately obvious how to view it in full screen, but thankfully, it is possible!
Turns out the answer is…. Single Tap. [facepalm!]
Just tap once on a PDF in Dropbox for iPad and your document will be shown in full-screen, and better yet, all of the other UI elements like the navigation bar fade away and you just see the document itself. So, while it was a little more difficult for me to find, once I discovered it I like the improvement in the full-screen view. I’m not sold on single-tap as a full-screen view gesture, but at least it’s there in some fashion.