ui: Save graph as image via context menu

bug id = 180

src/lib_gui/qt/graphics/QtGraphicsView.h

@@ -31,6 +31,8 @@ protected:
 
 	void wheelEvent(QWheelEvent* event);
 
+	void contextMenuEvent(QContextMenuEvent* event);
+
 signals:
 	void emptySpaceClicked();
 
@@ -38,6 +40,8 @@ private slots:
 	void updateTimer();
 	void stopTimer();
 
+	void exportGraph();
+
 private:
 	bool moves() const;
 
@@ -57,6 +61,8 @@ private:
 
 	std::shared_ptr<QTimer> m_timer;
 	std::shared_ptr<QTimer> m_timerStopper;
+
+	QAction* m_exportGraphAction;
 };
 
 #endif // QT_GRAPHICS_VIEW_H