How does the Nexus 4 rotating circular camera control work? Tapping the viewfinder or the blue shutter button of the Nexus 4 Android 4.2 camera app brings up the  rotating circular control shown in the screenshot. What is it used for? How does it work?
This is a new feature as of Android 4.2. It serves two purposes:


To focus your camera on what you click on
Long press it and you get a radial menu of different camera settings to change (flash on/off, etc). This is the exact same behavior as if you clicked the icon in the top right corner of your screenshot.