}
public void refresh() {
if (!everRefreshed) {
everRefreshed = true;
timerEvent = SimpleTimer.addPeriodicEvent("TopBarSpeedGraphicView", 1000, new TimerEventPerformer() {
public void perform(TimerEvent event) {
if ( downSpeedCanvas.isDisposed()){
timerEvent.cancel();
}else{
periodicUpdate();