1. A touch-sensor comprising: a substrate; a plurality of sensor electrodes disposed on the substrate, the plurality of sensor electrodes configured to sense an object proximate to the plurality of sensor electrodes; a processor coupled to the plurality of sensor electrodes, the processor configured to: detect a first object presence at a first position on the touch-sensor; detect a second object presence at a second position on the touch-sensor, the second object presence detectable a first elapsed time after an end of the first object presence, compare the first elapsed time with a first reference amount of time; compare a distance between the first position and the second position with a reference distance; and initiate a 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.