Hey guys, Im posting this here before I go to the Apple Store, see what you guys think. For two days now the screen have been displaying a weird intermittent white block on the left lower side every time that I have open 2 or more apps and do a three fingers swipe up to mission control and then back to one of the apps which are not running full screen. The only way it goes away it's to do the same thing again. What in the hell will this be? I attached a picture for you guys to see. Any feedback is appreciated. It is the latest model 27 inch Retina with the R390 card.