Topic on User talk:RaTcHeT302
Basically that when you use the remove borders feature, it'll stretch the image that's available inside the bordered window to make it full screen instead of actually drawing more pixels e to cover the entirety of your screen once the border is removed. Here, check it out:
With Full Window: http://i.imgur.com/4WFu95B.jpg In regular fullscreen: http://i.imgur.com/noBA4AS.jpg