1. A method for responding to a multiple-presence gesture, the method comprising: detecting a first presence of an object at a first position on the touch-sensor; detecting a second presence of an object at a second position on the touch-sensor, the second presence of an object occurring a first elapsed time after an end of the first presence; comparing the first elapsed time with a first reference amount of time; comparing a distance between the first position and the second position with a reference distance; and initiating a multi-presence gesture signal indicating an occurrence of a multiple-presence gesture responsive to each of a set of criteria being met, the set of criteria comprising the first elapsed time being less than the first reference amount of time and the distance between the first position and the second position being greater than the reference distance.