A touch-sensitive system comprises a light transmissive panel defining a touch surface and an opposite surface; an illumination arrangement comprising emitters configured to introduce light into the panel for propagation in the panel in an emission pattern; a light detection arrangement comprising detectors configured to receive the light propagating in the panel. A control unit is arranged to control the operation of the touch-sensitive system. The control unit executes a control method to monitor the light received in the light detecting arrangement for detection of touches on the touch surface, the touches attenuating the light propagating in the panel. The control method also selects a mode for the emission pattern in dependence of the occurrence of touches on the touch surface and controls the emission pattern in accordance with the selected mode.