Several questions:

1) The QwtPlotGLCanvas is based on QGLWidget, correct? And QGLWidget is now obsolete and there is a new class - QOpenGLWidget, will the QwtPlotGLCanvas be reworked to use a newer class then? If Yes, will there be any real improvement in speed for example?

2) is QwtPlotGLCanvas using a QPainter in order to draw to OpenGL?

3) Is there now some ongoing work with further testing/improvement of the OpenGL capabilities of Qwt library?