When you make a window in glut using glutCreateWindow it puts a top to the window? What if I want to do some OpenGL rendering without a window top?
This probably doesn't make much sense without a picture:
Essentially I want to remove this from the window.
The proper terminology for what you want is "undecorated window" or "borderless window". Unfortunately, I can't find any GLUT calls which let you control window decorations.
The closest I was able to find was glutFullScreen which, on X11 platforms, is often implemented by maximizing an undecorated window... but it'll re-decorate it if you un-maximize it.
This forum thread seems to confirm my conclusions.