Stop the display auto-rotating to the right or left side , without affecting automatic rotation (landscape mode) to the other side.
Since Android 2.2 (Froyo) the display is enabled to autorotate in both directions without any option to disable the autorotation to the right or the left side. It for right-handed persons does not make sense to keep the rotation to the right side active. The opposite is true for left-handed persons.
The switching off of the autorotation to one side, which is controlled automatically by this app, on the other hand allows usage or the phone when lying in bed on the autorotation-disabled side without having the screen turning.