Does the resolution scaling really scale the resolution or just the relative size of UI elements? If I show a photo on screen, I'd like that to use all the pixels in the display, not have that scaled. The highest "scaled" resolution option on the 13" is 1680x1050. I want more screen real estate than that, but I don't need to run native resolution either. My Asus 13.3" at 1920x1080 is just about right. Can I run that on a 13" MBP Retina with one of those graphics utilities out there? Thanks.