Subclassing QGLWidget using Qt Creator error -

i'm trying make simple subclass of qglwidget using qt creator, generated .h , .cpp file using qt creator wizard generated following code:

viewport.cpp

#include "viewport.h"  viewport::viewport(qobject *parent) :     qglwidget(parent) { } 

viewport.h

#ifndef viewport_h #define viewport_h  #include <qglwidget>  class viewport : public qglwidget {     q_object public:     explicit viewport(qobject *parent = 0);  signals:  public slots:  };  #endif // viewport_h 

i added qt += opengl .pro file got rid of of errors i'm left 2 don't understand:

/projects/tree_gen/qt_project/tree_gen-build-desktop-qt_4_8_4_in_path__system__debug/../tree_gen/viewport.cpp:4: error: invalid conversion 'qobject*' 'qwidget*'  /projects/tree_gen/qt_project/tree_gen-build-desktop-qt_4_8_4_in_path__system__debug/../tree_gen/viewport.cpp:4: error:   initializing argument 1 of 'qglwidget::qglwidget(qwidget*, const qglwidget*, qt::windowflags)' 

ive not changed anything, trying compile qt gave me, ideas?

qglwidget widget , takes qwidget* parent, it's idea use kind of parent widget class too: explicit viewport(qwidget *parent = 0); //don't forget modify .cpp too