An input panel for an electronic device, including an arrangement of buttons, wherein each button is actuated when pressed, providing input to an electronic device, and a sensor, detecting location of a user's finger above the buttons, the sensor including a housing, a printed circuit board, light emitters and photodiode detectors, lenses mounted in the housing in such a manner that, when the housing is mounted along an edge of the arrangement, the lenses direct light from the emitters along a plane above the buttons, and direct light from the plane, reflected toward the lenses by an object inserted into the plane, onto the detectors, a processor configured to identify a location in the plane at which the object is inserted based on the detections of light reflected by the object, and a communications port configured to output the identified location to the electronic device.