@Override
 public HandlerRegistration addOpenHandler(OpenHandler<ConfirmDialog> handler) {
   return dialogBox.addHandler(handler, OpenEvent.getType());
 }
 /** Adds a handler for the Cancel button click event */
 public HandlerRegistration addCancelHandler(CancelHandler handler) {
   return dialogBox.addHandler(handler, CancelEvent.getType());
 }
 @Override
 public HandlerRegistration addCloseHandler(CloseHandler<ConfirmDialog> handler) {
   return dialogBox.addHandler(handler, CloseEvent.getType());
 }
 /** Adds a handler for the OK button click event */
 public HandlerRegistration addOkHandler(OkHandler handler) {
   return dialogBox.addHandler(handler, OkEvent.getType());
 }