PopupCanvas.java 文件源码

@SuppressWarnings({ "unchecked", "rawtypes" })
@Override
public HandlerRegistration addMouseDownHandler(MouseDownHandler handler) {
    eventHandlers.put(handler, (DomEvent.Type) MouseDownEvent.getType());
    if (canvas != null) {
        canvas.addDomHandler(handler, MouseDownEvent.getType());
    }
    return null;
}