How to simulate a retina display (HiDPI mode) in Mac OS X 10.8 Mountain Lion on a non-retina display?

Question

How can you simulate a retina display (HiDPI mode) in Mac OS X 10.8 Mountain Lion on a non-retina display?

Answer 1

1. Search for, download, and install Apple's free Additional Tools for Xcode 8 (for previous Xcode releases search for Graphics Tools for Xcode according to your version).
   Note: free Apple Developer account required.
2. Launch Quartz Debug application.
3. Go to menu: Window ---> UI Resolution.
4. Check Enable HiDPI display modes.
5. Quit Quartz Debug.
6. Open System Preferences.
7. Select Displays icon.
8. If using multiple display, select the configuration window on the display you wish to simulate HiDPI mode on.
9. Under Resolution:, select Scaled radio button.
10. Find a desired resolution postfixed with (HiDPI) and select it.
11. Your display is now running in HiDPI mode, simulating a retina display.

Source: High Resolution Guidelines for OS X