#include <QApplication>
#include <QKeyEvent>
#include <QOpenGLWidget>
#include <QOpenGLWindow>

#include <QPainter>
#include <QDebug>
#include <QMenu>

class Widget : public QWidget
{
protected:
  void contextMenuEvent(QContextMenuEvent* e)
  {
    QMenu m;
    m.addAction("Item 1");
    m.addAction("Item 2");
    m.addAction("Item 3");

    m.exec(e->globalPos());
  }

  void keyPressEvent(QKeyEvent* e)
  {
    if(e->key() == Qt::Key_Escape)
    {
      close();
    }
    else if(e->key() == Qt::Key_F)
    {
      setWindowState(windowState() ^ Qt::WindowFullScreen);
    }
  }
};

class Dummy : public QWidget
{
public:
  Dummy()
  {
    setMinimumSize(100,100);
  }

protected:
  void paintEvent(QPaintEvent*)
  {
    QPainter p(this);
    p.setPen(Qt::NoPen);
    p.setBrush(Qt::green);

    p.drawRect(rect());
  }
};

#include <QGridLayout>

int main(int argc, char *argv[])
{
  QApplication a(argc, argv);

  Widget w;

  QGridLayout*const lay = new QGridLayout;
  lay->addWidget( new Dummy, 0, 0 );
  lay->addWidget( new Dummy, 0, 1 );
  lay->addWidget( new Dummy, 0, 2 );
  lay->addWidget( new Dummy, 1, 0 );
  lay->addWidget( new QOpenGLWidget, 1, 1 );
  lay->addWidget( new Dummy, 1, 2 );
  lay->addWidget( new Dummy, 2, 0 );
  lay->addWidget( new Dummy, 2, 1 );
  lay->addWidget( new Dummy, 2, 2 );

  w.setLayout(lay);

  w.show();

  return a.exec();
}