Testing graphics on a Retina display can be time consuming, but it does not have to be. ResolutionTab takes the hassle out of constantly going back in
to System Preferences and switching between different Display modes.
In order to use ResolutionTab, you need to have enabled virtual HiDPI display modes.Learn More
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:
Launch Terminal app located in your /Applications/Utitlities folder.
Copy and paste the following command:
sudo defaults write /Library/Preferences/com.apple.windowserver DisplayResolutionEnabled -bool YES
You may be prompted for the password.
Log out and log in again.
Done. HiDPI is activated and ResolutionTab will work properly.