Qt qml with raw OpenGL containing FBO

[Montjet]

#edit
Oh, I found solution - window->openglContext()->defaultFramebufferObject().

Hi,
I have engine based on raw OpenGL, which contains Frame Buffer Objects.
Wiithout qt everything works fine.
I wrote simple test code with glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);

SceneRenderer.h:

        class SceneRenderer : 
            public QObject
        {
            Q_OBJECT;

        public:
            SceneRenderer();
            ~SceneRenderer();

            void SetWindow(QQuickWindow* window);
            QQuickWindow* GetWindow() const { return m_window; }

        public slots:
            void Render();

        private:
            QQuickWindow* m_window;

        };

SceneRenderer.cpp:

        SceneRenderer::SceneRenderer() :  
            m_window(nullptr)
        { 
        }

        SceneRenderer::~SceneRenderer()
        {
        }

        void SceneRenderer::SetWindow(QQuickWindow* window)
        { 
            m_window = window; 
        }

        void SceneRenderer::Render()
        {
            glViewport(0, 0,
                m_window->width() * m_window->devicePixelRatio(),
                m_window->height() * m_window->devicePixelRatio()
            );
			
            glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
            glClearColor(0.0f, 0.0f, 1.0f, 1.0f);
            glClear(GL_COLOR_BUFFER_BIT);
            m_window->resetOpenGLState();
            m_window->update();

        }

SceneView.h:

        class SceneView : public QQuickItem
        {
            Q_OBJECT;

        public:
            explicit SceneView(QQuickItem* parent = nullptr);
            ~SceneView();

        public slots:
            void Synchronize();
            void Cleanup();

        private slots:
            void HandleWindowChanged(QQuickWindow* window);

        private:
            std::unique_ptr<SceneRenderer> m_renderer;

        };

SceneView.cpp:

        SceneView::SceneView(QQuickItem* parent) :
            QQuickItem(parent),
            m_renderer(nullptr)
        {     
            connect(this, &QQuickItem::windowChanged, 
                this, &SceneView::HandleWindowChanged);
        }

        SceneView::~SceneView()
        {
        }

        void SceneView::HandleWindowChanged(QQuickWindow* window)
        {
            if (window) 
            {
                connect(window, &QQuickWindow::beforeSynchronizing, 
                    this, &SceneView::Synchronize, Qt::DirectConnection);
                connect(window, &QQuickWindow::sceneGraphInvalidated, 
                    this, &SceneView::Cleanup, Qt::DirectConnection);
                window->setClearBeforeRendering(false);
            }
        }

        void SceneView::Synchronize()
        {
            if (m_renderer == nullptr)
            {
                m_renderer = std::make_unique<SceneRenderer>();
                connect(window(), &QQuickWindow::beforeRendering,
                    m_renderer.get(), &SceneRenderer::Render,
                    Qt::DirectConnection);
            }
            m_renderer->SetWindow(window());
        }

        void SceneView::Cleanup()
        {
            m_renderer.release();
            m_renderer = nullptr;
        }

Main window format:

            QSurfaceFormat format;
            format.setMajorVersion(4);
            format.setMinorVersion(5);

            // CoreProfile is not supported by engine
            format.setProfile(QSurfaceFormat::CompatibilityProfile);
            format.setDepthBufferSize(24);
            format.setStencilBufferSize(8);
            format.setSamples(4);
            m_workspaceWidget->setFormat(format);

Result: white window, not blue...
Engine is built as a shared library, so It can not be integrated with qt functions.
How can I get initial frame buffer object or how to fix it?