A layout is a special kind of group, which shown inside a container. Each layout represents an appearance for that window. Layouts give you the ability to design differnt looks for the same container (or window). However, only one layout can be visible at a time. You must toggle among layouts you defined. An example is the normal mode and windowshade mode in the Default skin.

* The top image is using normal layout and the bottom is using the windowshade layout.
Lets look at the Simple Tutorial xml code for layout: