For the mentioned upcoming release, here are minor issues I came around. Nothing serious, and too small issues to create a new topic for them alone.
1) The enum GetTextureParameter doesn't contain GL_TEXTURE_COMPRESSED.
2) Glu.ErrorString expects different type as parameter, than what is returned by GL.GetError(); Unnecessary cast? Don't see any other use for these commands.
public bool KeyRepeat
Documentation unclear about "on", true/false might be better.
4) GL.Color could use a Vector overload, colors can be nicely stored in Vector3/4. The function was also behaving a bit weird always expecting (int) for fixed-point types. E.g. (byte)255 for RGB would result in black as it got cast to int32. Anything but byte/float is not really useful?
5) GL.Material could aswell use a Vector4 overload. I understand why this is difficult for all functions where modes can expect different types for their own parameters, but I think this is a special case where this would make sense. How about adding GL.Materialv4, which can be used for convenience with a Vector4 for specifying colors (ambient/diffuse/specular/emissive), where shininess can still be set through default GL.Material().
This is just something to consider, the current implementation is fine.
Ironically 3) was the point where I decided that it'd be quicker to implement that "keystroke manager" in a few minutes than going through documentation. All I wanted was Glut-like handling for a handful of toggles and getting other functions further, no offense/critique against your design - just a subjective decision for that small project.