A computer-implemented process for controlling a touch-sensitive computing device comprising a processor, a touch-sensitive surface, a display, and an inertial measurement unit, or accelerometer, or gyroscope, the computer-implemented process comprising: receiving sensor signals, from the touch-sensitive surface of the touch-sensitive computing device, representing a grip of a primary user on the touch-sensitive computing device; receiving sensor signals, from the touch-sensitive surface of the touch-sensitive computing device, representing a grip of a secondary user on the touch-sensitive computing device at the same time the signal for the grip of the primary user is received, the received sensor signals having been determined to represent the grip of the primary and secondary user based on contact of fingers or hand on the touch-sensitive surface of the touch-sensitive computing device and based on a database of grip patterns; correlating the sensor signals for the grips of the primary and secondary users (1702, 1706) to determine that: the primary user and the secondary user are concurrently sharing the touch-sensitive computing device, while the grips of the primary and secondary users remain concurrent, and the touch-sensitive computing device is being handed off from the primary user to the secondary user when an orientation, sensed using the inertial measurement unit, or accelerometer, or gyroscope of the touch-sensitive computing device, of the display of the touch-sensitive computing device is approximately level while grips of the primary and secondary users remain concurrent, and then the grip of the primary user is no longer detected; and using the determination to initiate a command in an application executing on the touch-sensitive computing device. receiving sensor signals, from the touch-sensitive surface of the touch-sensitive computing device, representing a grip of a primary user on the touch-sensitive computing device; receiving sensor signals, from the touch-sensitive surface of the touch-sensitive computing device, representing a grip of a secondary user on the touch-sensitive computing device at the same time the signal for the grip of the primary user is received, the received sensor signals having been determined to represent the grip of the primary and secondary user based on contact of fingers or hand on the touch-sensitive surface of the touch-sensitive computing device and based on a database of grip patterns; correlating the sensor signals for the grips of the primary and secondary users (1702, 1706) to determine that: the primary user and the secondary user are concurrently sharing the touch-sensitive computing device, while the grips of the primary and secondary users remain concurrent, and the touch-sensitive computing device is being handed off from the primary user to the secondary user when an orientation, sensed using the inertial measurement unit, or accelerometer, or gyroscope of the touch-sensitive computing device, of the display of the touch-sensitive computing device is approximately level while grips of the primary and secondary users remain concurrent, and then the grip of the primary user is no longer detected; and using the determination to initiate a command in an application executing on the touch-sensitive computing device. the primary user and the secondary user are concurrently sharing the touch-sensitive computing device, while the grips of the primary and secondary users remain concurrent, and the touch-sensitive computing device is being handed off from the primary user to the secondary user when an orientation, sensed using the inertial measurement unit, or accelerometer, or gyroscope of the touch-sensitive computing device, of the display of the touch-sensitive computing device is approximately level while grips of the primary and secondary users remain concurrent, and then the grip of the primary user is no longer detected; and using the determination to initiate a command in an application executing on the touch-sensitive computing device.