New Post: SharpGL FBO and High Res Texture Question

Perhaps the reason that OpenGL2_1 works and OpenGL4_4 doesn't, is the code perhaps uses deprecated commands.
In my code I found TexCoord appears to be deprecated (works in OpenGL2_1, but not OpenGL4_4).

https://www.opengl.org/registry/oldspecs/gl.spec - search this document using "deprecated" to find old commands.

Support is still there:
https://developer.nvidia.com/opengl-driver