Trackball sensitivity refers to the amount of trackball movement that is required for the system to identify the movement as a navigation event, and to dispatch a navigation event to the software layer. The BlackBerry® device hardware measures physical trackball movement using units called ticks. When the number of ticks along an axis surpasses the threshold of the system or a BlackBerry® Java Application, a navigation event along that axis is dispatched to the software layer, and the system resets the tick count to zero. Tick counts are also reset to zero after a certain amount of idle time passes.
You can use the TrackBall API to set the trackball sensitivity. High trackball sensitivity equates to a smaller tick threshold, which means that small trackball movements will trigger navigation events. Conversely, low trackball sensitivity equates to a larger tick threshold, which means that larger trackball movements are required to generate navigation events.