1. A method, comprising: associating, in a computer executing a non-tactile three dimensional (3D) user interface, multiple regions, comprising at least first and second regions, within a field of view of a sensing device coupled to the computer with respective states of the non-tactile 3D user interface, comprising at least first and second states associated respectively with the first and second regions; receiving a set of multiple 3D coordinates representing a hand movement from the first region to the second region; and responsively to the movement, transitioning the non-tactile 3D user interface from the first state to the second state.