I've got a 2012 classic MBP (non-retina) and I think the max resolution is supposed to be 1280 x whatever. When I use the Mac in clamshell mode, the external monitor displays much more screen real estate than the native display (It's 1920 x 1280). When I disconnect the external monitor, my MBP displays lower resolution and icons are larger as I would expect them to be. Here's my question: when I connect the MBP to the external monitor and do not close the laptop, the screen on the MBP looks exactly like the external monitor. The icons and screen real estate are the same. So is my MBP displaying 1920 x 1280? And if so, doesn't that mean the display is capable of displaying full HD all the time?