Dropbox's UWP application for Windows 10 is one of the highlights of the platform, working absolutely brilliantly on Windows 10 Mobile, though today's update is just as much about also supporting Xbox games consoles (part of the 'universal' platform). We do get an Excel spreadsheet viewer and Grid view drag and drop though, on the phone, so it's all good...
Full support of Xbox One with a new TV UI, support of gamepad and media remote.
Drag and drop added to grid view.
Here's the new version of Dropbox UWP in action:
Tapping on an Excel file now launches an integral viewer, with the option to save locally or open to a local application, etc. The viewer has multi-touch zoom too, so you can dive in and pan around as needed.
Dragging and dropping items around isn't intuitive in my experience, but hey, at least long pressing gives the right context-sensitive options; (right) it's worth noting again that this is the official Dropbox application, even though programmed by Rudy Huyn, and as such all the help links go through to the Dropbox web site.