Container*
createControlPanel(osgViewer::View* view)
{
    ControlCanvas* canvas = ControlCanvas::getOrCreate(view);
    VBox* vbox = canvas->addControl(new VBox());
    vbox->setChildSpacing(10);
    return vbox;
}
int
main(int argc, char** argv)
{
    // allocate pager threads based on CPU configuration.
    int cores = Registry::capabilities().getNumProcessors();
    osg::DisplaySettings::instance()->setNumOfDatabaseThreadsHint( osg::clampAbove(cores, 2) );
    osg::DisplaySettings::instance()->setNumOfHttpDatabaseThreadsHint( osg::clampAbove(cores/2, 1) );

    // parse the command line.
    osg::ArgumentParser arguments(&argc,argv);
    osgViewer::Viewer viewer(arguments);

    // set up the motion model.
    viewer.setCameraManipulator( new EarthManipulator() );

    // simple UI.
    VBox* vbox = new VBox();
    vbox->setMargin( 3 );
    vbox->setChildSpacing( 5 );
    vbox->setAbsorbEvents( true );
    vbox->setHorizAlign( Control::ALIGN_RIGHT );
    vbox->setVertAlign ( Control::ALIGN_BOTTOM );

    // Control instructions:
    Grid* grid = vbox->addControl( new Grid() );
    grid->setControl( 0, 0, new LabelControl("Pan:"));
    grid->setControl( 1, 0, new LabelControl("Left mouse"));
    grid->setControl( 0, 1, new LabelControl("Zoom:"));
    grid->setControl( 1, 1, new LabelControl("Right mouse / scroll"));
    grid->setControl( 0, 2, new LabelControl("Rotate:") );
    grid->setControl( 1, 2, new LabelControl("Middle mouse"));
    grid->setControl( 0, 3, new LabelControl("Go to:"));
    grid->setControl( 1, 3, new LabelControl("Double-click"));

    ControlCanvas::getOrCreate(&viewer)->addControl(vbox);

    // Load an earth file
    osg::Node* node = MapNodeHelper().load(arguments, &viewer);
    if ( !node )
        return usage( "Failed to load earth file." );
    viewer.setSceneData( node );


#ifdef Q_WS_X11
    // required for multi-threaded viewer on linux:
    XInitThreads();
#endif


    QApplication app(argc, argv);

    QWidget* viewerWidget = new ViewerWidget( &viewer );
    
    QMainWindow win;
    win.setWindowTitle( "osgEarth -- The #1 Open Source Terrain SDK for Mission-Critical Applications" );
    win.setCentralWidget( viewerWidget );
    win.setGeometry(100, 100, 1024, 800);

    win.statusBar()->showMessage(QString("osgEarth.  Copyright 2014 Pelican Mapping.   Please visit http://osgearth.org"));

    win.show();
    app.exec();
}