How can I force specific HiDPI modes? I have a 13" MBP (Early 2011) plugged it to a Dell U2711 monitor via DisplayPort.

I have successfully enabled HiDPI mode, using Quartz Debug the problem is that the screen won't run at the HiDPI equivalent of the screen's native resolution. i.e 1440x720 HiDPI (2560x1440). The screen's maximum resolution of 2560x1440 is recognised &amp; working.



The best it will do is 960x720HiDPI (1920x1440), which seems strange as most of the documentation suggests HiDPI will only work at pixel doubling resolutions.



Is it possible to force the MBP to run the display at 1440x720 HiDPI on a screen that supports 2560x1440 native pixel resolution?
After a lot of messing about I managed to get this working in two ways.


The first is by using the Retina Display Manager I found on reddit.
This gives a menu with all the available display modes, but try the second method first.
Screenshot 1 (Warning, large file)
The second I found after using Retina Display Manager, to my surprise the Displays pane in System Preferences was reporting it was running in 720p mode.
This mode is actually 1280x720 HiDPI (2560x1440).
Screenshot 2 (Warning, large file)


Yay!

I was going to embed screenshots of these new menus, but they are now insanely huge due to HiDPI mode, so I just linked to them instead.