OPERATING A TOUCH SCREEN CONTROL SYSTEM ACCORDING TO A PLURALITY OF RULE SETS

An electronic device comprises a display screen configured for displaying images, a touch sensor configured to detect user input in a sensing region, a host processing system and a touch screen control system. The touch screen control system comprises control circuitry and a memory configured for holding rules. The control circuitry is configured for updating the display screen in response to image data from the host processing system and for operating according to a first set of rules held in the memory. The control circuitry is also configured, in response to receiving an indication from the host processing system, for switching from operating according to the first set of rules to operating according to a second set of rules.