OpenGL nothing displayed

[QT-static-prgm]

Hey,

i have a problem with my project. I started with it using glew and glfw. But those were very limited, so i want to use Qt now.

Most of my code is just copied from the old Project to my new one
I have no idea, why it does not work, but maybe someone of you can tell me. I'm not very good with OpenGL, but i think i understand the basics well and i don't see any reason why it does not work.
The file import function is 100% the same from the old project. I just switched from my own tga importer to QImage, because i think Qt is the better implementation for it. So you may focus on the OpenGlViewer widget class it need to be something there.
If you need any further information, or if you have an idea about how to debug such an problem, let me know.

[QT-static-prgm]

i tried to use as many Gl functions instead of qt to use my old working code. But there is still nothing displayed. That's driven my crazy.

https://git.rwth-aachen.de/carstenf/OpenGL/tree/master/MeshViewerQt

Is there any way to see the content of the buffer while runtime???