// add the state manipulator
viewer->addEventHandler( new osgGA::StateSetManipulator(viewer->getCamera()->getOrCreateStateSet()) );
// add the thread model handler
viewer->addEventHandler(new osgViewer::ThreadingHandler);
// add the window size toggle handler
viewer->addEventHandler(new osgViewer::WindowSizeHandler);
// add the stats handler
viewer->addEventHandler(new osgViewer::StatsHandler);
// add the record camera path handler
viewer->addEventHandler(new osgViewer::RecordCameraPathHandler);
// add the LOD Scale handler
viewer->addEventHandler(new osgViewer::LODScaleHandler);
// add the screen capture handler
viewer->addEventHandler(new osgViewer::ScreenCaptureHandler);