bus.register(this, AnnotateROI.class);
    public void setContext(Registry ctx)     {        registry = ctx;        EventBus bus = registry.getEventBus();        bus.register(this, LoadImage.class);        bus.register(this, ImageLoaded.class);        bus.register(this, ImageRendered.class);        bus.register(this, AddROICanvas.class);        //bus.register(this, DisplayViewer3D.class);        control = new ViewerCtrl(this);    }