The solution for to refactor the way that events are checked so I add a bool return type to checkEvents() method across osgViewer::GraphcisWindow, osgGA::Devive and osgViewer::Viewer/CompositeViewer classes
Added template readFile(..) function to make it more convinient to cast to a specific object type.
Added support for osgGA::Device to osgViewer.
Added sdl plugin to provides very basic joystick osgGA::Device integration.