Hi folks. I got a mini displayport to displayport cable so that I could mirror my macbook air on one of my 23" Dell displays. The problem is that I can only get 1920x1080 to work on the external monitor in extended mode and not in mirrored. When I use mirrored both displays use 1366x768, even if the external is set to 1920x1080 and ticked as such. I have tried various resolutions on the air itself to see if I can force 1080p on the external display but no joy. It's mirrored or nothing for me so please help!!!!!!! Thanks in advance.