code: public void setBusy(String message) {
          busyMessage = message = StrUtil.formatMessage(message);
  
          if (busyDisabled) {
              busyPending = true;
          } else if (message != null) {
              disableActions(true);
              ClientUtil.busy(container, message);
              busyPending = !isVisible();
          } else {
              disableActions(false);
              ClientUtil.busy(container, null);
              busyPending = false;
          }
      }
docs: If message is not null, disables the plugin and displays the busy message. If message is
  null, removes any previous message and returns the plugin to its previous state.
  
  @param message The message to display, or null to clear previous message.