Quote Originally Posted by didier View Post
A this time, no. I have just written this piece of code.


Qt Code: 
  1. class GLWidget :public QGLWidget
  2. {
  3. Q_OBJECT
  4.    public:
  5.    GLWidget(QWidget* argParent = 0,
  6.             const QGLWidget* argShareWidget = 0,
  7.             Qt::WindowFlags argFlags = 0 );
  8.  
  9.     signals:
  10.     void sizeChanges(QSize const&);
  11.     void doubleClick(QPoint const&);
  12.     void click(QPoint const&);
  13.  
  14.     protected:
  15.     void initializeGL();
  16.     void resizeGL(int argWidth, int argHeight);
  17.     void mouseDoubleClickEvent(QMouseEvent* event);
  18.     void mouseReleaseEvent(QMouseEvent* event);
  19.     void paintGL();
  20.  
  21. };
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Qt Code: 
  1. #include "../include/GLWidget.h"
  2.  
  3. GLWidget::GLWidget(QWidget* argParent,
  4.                     const QGLWidget* argShareWidget,
  5.                     Qt::WindowFlags argFlags)
  6.  
  7.                     :QGLWidget(argParent,
  8.                                argShareWidget,
  9.                                argFlags)
  10. {
  11. }
  12.  
  13. void GLWidget::initializeGL()
  14. {
  15. }
  16.  
  17. void GLWidget::resizeGL(int argWidth, int argHeight)
  18. {
  19.    emit sizeChanges(QSize(argWidth, argHeight));
  20. }
  21.  
  22.  
  23. void GLWidget::paintGL()
  24. {
  25. }
  26.  
  27. void GLWidget::mouseDoubleClickEvent(QMouseEvent* event)
  28. {
  29. emit doubleClick(event->pos());
  30. }
  31.  
  32. void GLWidget::mouseReleaseEvent(QMouseEvent* event)
  33. {
  34.    emit click(event->pos());
  35. }
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I've believed, an instant, it's because my OpenGL implementation is 4.1 and Qt 4.6.3 wouldn't recognize OpenGL 4.1 because of enum QGLFormat::OpenGLVersionFlag's definition.

About glGetString(). The problem is over. I've discovered glContext is inititialized in after QGLWidget() constructor. In paintGL(), it works well.
Good to know about QGLFormat::OpenGLVersionFlag.