This is not possible with the device as it stands BUT: A possible solution is to extend the multitouch area around the sides and back(to sense the grip) and ca

This is not possible with the device as it stands BUT: A possible solution is to extend the multitouch area around the sides and back(to sense the grip) and cancel out any grip finger movements. So floating pointing finger still is sensed but slight movements in gripping hand should not wreck things.