1. A computing device, comprising: a display; a sensor subsystem for detecting off-surface objects; memory having instructions stored on it which when run on a processor, causes the processor to perform the steps of: detecting an off-surface object using the sensor subsystem; determining a position and a shape of said detected off-surface object; matching the determined position with a set of reference zones and the determined shape with a set of reference poses to thereby determine a gesture state; detecting changes in the determined position and shape using the sensor subsystem; matching said changes in the determined position with transitions between said reference zones and matching said changes in determined shapes with transitions between said reference poses to thereby determine a transition between gesture states; and, instructing a user interface to provide feedback based on the determined transition between gesture states.