Wife has a 15" macbook pro retina that's a few years old. I want to get either a dual monitor set up or a large wide screen monitor that could do a split screen. I have no idea what I need to get this done and am looking for advice on what I need to get. I am not familiar with the macbook pro's ability to do dual monitors or split screen one monitor. Ideally have something like one monitor showing email all the time and the other one being the main working monitor. Any advice would be greatly appreciated!