The Patterns interface gives you access to computer-generated patterns allowing you to calibrate screen geometry, detect dot-scroll
and the use of the White Wash interface.
The White Wash interface is used by displays that can easily get screen-burn (such as Plasma displays, where you see a semi-translucent
image burnt in). Allowing the White Wash interface to run for several hours may reverse some of the screen-burn damage.
Accessing the Patterns interface is done by pressing Shift+"P" on the keyboard to cycle through the available pattern modes.