Unfortunately, last I checked, most OSes don't properly handle subpixel antialiasing on monitors in non-standard orientations. They use the assumption that the

Unfortunately, last I checked, most OSes don't properly handle subpixel antialiasing on monitors in non-standard orientations. They use the assumption that the red subpixel is to the left of the right one, which is violated when you rotate the monitor. See here, for example: http://superuser.com/questions/265413/portrait-monitor-orientation-causes-text-blurring http://superuser.com/questions/265413/portrait-monitor-orien....