ProModeCurrentGet clears undo stack

I have a popupmenu listener which implements the object toolkit callback as

  void OnPopupmenuCreate(pfcPopupmenu_ptr spMenu)

  {

    xstring name = spMenu->GetName();

    cout << "OnPopupmenuCreate name=" << name << endl;

    ProMode mode;

    ProError error = ProModeCurrentGet (&mode );

    cout << "mode = " << mode << endl;

  }

Unfortunately the call to ProModeCurrentGet (&mode ); clears the undo stack wihtou the call the undo stack remains intact. How can I determine which mode Creo is in so that I know whether to add to the popup menu or not without clearing the undo stack? Is there at least one version of creo where this call is not a problem?