#include <QWidget>
#include <QtOpenGL/QGLWidget>
+#include <QtOpenGL/QGLFunctions>
#include <QtOpenGL/QGLShaderProgram>
#include <QMatrix4x4>
class Mesh;
class Backdrop;
-class Canvas : public QGLWidget
+class Canvas : public QGLWidget, protected QGLFunctions
{
Q_OBJECT