I'd like to be able to see a preview of a high quality renders on a big screen fully than only see small areas full size in areas on a 1920x1080 monitor.

On my 4K screen if I press "maximize" it stays at 1920x1080". I'm Developing content for the marketplace and need the ability to see as much detail as possible for quality check. This is also important to see in realtime how the finished render will look on 4K monitors.