Hooked up the Surface Pro 2 to my Apple LED Cinema display (non-thunderbolt). The "recommended" resolution is 2560x1440.
Works but the icons are really grainy. With Outlook 2013 open the whole application interface is not really sharp. Not at all what I was expecting. Perhaps its a driver issue?
I double checked the resolution with the MacBook Air using the same LED Cinema display; a LOT sharper.
No. It is because Windows applies different DPI on each display, and scales like a picture, the content of the program that is on a display not matching the DPI setting of the primary display.
To fix this problem, set both displays to the same DPI level, or better yet, 100% DPI, which will also make non-high-DPI aware software look sharp as well.
Right-click on the desktop, and select "Screen resolution", then on "Make text and other items larger or smaller", and slide the bar to right most (smaller), which is 100% DPI.
Hit Apply and restart your system.