code: public int waitForWindowPageChanged(String windowName) {
      if (getScopeServices().getConnection() == null) {
        throw new CommunicationException(
            "waiting for a window failed because Opera is not connected.");
      }
  
      return getScopeServices().waitForDesktopWindowPageChanged(windowName,
                                                                OperaIntervals.WINDOW_EVENT_TIMEOUT
                                                                    .getMs());
    }
docs: Waits until new page is shown in the window is shown, and then returns the window id of the
  window
  
  @param windowName - window to wait for shown event on
  @return id of window