glutFullScreen man page
glutFullScreen — Resize the current window to cover the entire screen
OpenGLUT - window
The glutFullScreen() function resizes the window to cover the entire screen and hide window decorations such as title bars and icons.
The desktop resolution is not affected by a call to glutReshapeWindow() or glutFullScreen().
The size of windows is ultimately determined by the windowing system. Therefore, a fullscreen request by an OpenGLUT application may not necessarily succeed or take immediate effect.
Not applicable to offscreen or subwindows.
glutInit(3) glutInitWindowPosition(3) glutInitWindowSize(3) glutGet(3) glutPositionWindow(3) glutReshapeWindow(3)