ResolutionTab is a menu bar app for fast switching between standard and ultrahigh-resolution 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.
PLEASE NOTE:
In order to use ResolutionTab, you need Xcode and a developer tool named Quartz Debug that enables virtual HiDPI modes in OS X. To access it, do the following: 1. Open Xcode, 2. In the top menu click Xcode > Open Developer Tool > More Developer Tools, 3. Enter your Apple ID, 4. Under Graphics Tools for Xcode (March 2012) download the attached DMG, 5. Install the downloaded tool, 6. Then in Xcode follow Xcode > Open Developer Tool > Quartz Debug, 7. In the menu open Window > UI Resolution and enable the checkbox. Voila! HiDPI is activated and now you can test apps and website in Retina mode.