Possibly relevant, from openGL.org:
"How you access overlay planes depends on the windowing system interface. While GLUT 3.7 has entry points defined for the use of overlays, currently the entry points are disabled. To use overlays, your application needs to use WGL, GLX, or another platform-specific interface."
I happen to be using GLUT so whatever I was doing wrong, it was bound for failure anyway. Womp.