Can we enable 1920 X 1200 HiDPI mode on OS X 10.9.2?

Question

with RDM, we can enable a number of displays such as the Retina 15" or Retina 13" to do the 1920X1080 HiDPI but with some screen area blacked out. Can we enable 1920 X 1200 by overriding some system files? Thanks.

Solution

Here's some more detail of how I did it on my Macbook Pro Retina 2012:

I was using RDM, but had no 1920x1200 HiDPI mode (the highest was 1920x1080).

I downloaded and installed SwitchResX. Then clicked "Color LCD", and "Custom Resolution". Then click the "+" icon and add in a new Scaled Resolution of 3840x2400:

Close SwitchResX and make sure it asks to save (you'll need to enter an Admin password). Then restart the Macbook.

Then RDM shows this in the menu:

Squint and enjoy!