add: case 'f': { mgr->setNavigationMode(Navigator::FLY); } break;  case 't': { mgr->setNavigationMode(Navigator::TRACKBALL); } break;
context: void keyboard(unsigned char k, int x, int y){    switch(k)    {        case 27:            {            OSG::osgExit();            exit(0);        }        break;    }}