ResolutionTab is a menu bar app for fast switching between Standard & HiDPI display modes.
Modern apps and websites should look great on Retina displays, so we have to test them in both standard and ultrahigh resolution modes. But when you configure your display in System Preferences, it takes plenty of time to switch from the standard to the HiDPI mode and vice versa. ResolutionTab is a minimal app living in the menu bar that toggles your Mac between Retina and non-Retina resolutions in one click.
— 15" MacBook Pro Retina is compatible with HiDPI modes by default, so ResolutionTab will work out of the box.
— 11" MacBook Air is not compatible with HiDPI. The screen is too small, so resolution would drop below the minimum required by OS X.
— In all other cases, you have to enable virtual HiDPI modes manually.
Here is how to do this with Administrative privileges:
1. Launch Terminal app located in your /Applications/Utitlities folder.
2. Type sudo defaults write /Library/Preferences/com.apple.windowserver DisplayResolutionEnabled -bool YES.
3. Log out and log in again.
Done. HiDPI is activated and ResolutionTab will work properly.