Can't use QPainter in QOpenGlWidget with OpenGL 3.3

[Gerx]

I'm trying to use QPainter in my QOpenGLWidget. But it only works with 3.0 OpenGL version. What is the problem?

Here is my code.

#include <QApplication>
#include <Q
MainWindow>
#include "window.h"

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

  QSurfaceFormat format;

  format.setRenderableType(QSurfaceFormat::OpenGL);
  format.setProfile(QSurfaceFormat::CoreProfile);
  format.setVersion(3,3);

  // Set widget up
   Window *widget = new Window;
   widget->setFormat(format);

  // Set the window up
  QMainWindow window;
  window.setCentralWidget(widget);
  window.resize(QSize(800, 600));
  window.show();

  return app.exec();
}

If i'll do setVersion(3,0) everything will work fine. But my shaders won't start up.

And QOpenGLWidget subclass

#define WINDOW_H

#include <QOpenGLWidget>
#include <QOpenGLFunctions>

class QOpenGLShaderProgram;

class Window : public QOpenGLWidget,
               protected QOpenGLFunctions
{
  Q_OBJECT

// OpenGL Events
public:

  void initializeGL();
  void resizeGL(int width, int height);
  void paintGL();

};

#endif // WINDOW_H

and simpliest example.

#include <QPainter>


void Window::initializeGL()
{}

void Window::resizeGL(int width, int height)
{}

void Window::paintGL()
{
      QPainter p(this);
      p.setPen(Qt::red);
      p.drawLine(rect().topLeft(), rect().bottomRight());
}