again here some news:
We have a main class, a render class and a AppWindow class (this class we did make on purpose because we need access from some other classes too).
In the main class we call "AppWindow Init" which executes this code:
App.Create(sf::VideoMode(width, height), "Title"/*, sf::Style::Fullscreen*/);
App.SetCursorPosition(getWidth()/2, getHeight()/2);
and next in the main class again the Render.initGL function is called which executes some GL Stuff like Depth_Test, Lighting and Texture enable, Smooth Shading, etc... and also this 2 lines:
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
glEnable(GL_PERSPECTIVE_CORRECTION_HINT);
If we now disable the 2 lines with comments then the INVALID Error disappears, we dont know why but maybe this gives you an idea, Laurent?
A Screenshot of the Error:
-tno