public void start() {
if (eventHandlers.size() > 0) {
return; //already started
}
eventHandlers.add(target.addPhotoClickHandler(new PhotoClickHandler() {
public void photoClicked(PhotoClickEvent event) {
PhotoFocusEvent evt = new PhotoFocusEvent();
evt.setPhoto(event.getPhoto());
evt.setPhotoIndex(event.getPhotoIndex());
lastFocusEvent = evt;