SDL-1.2 VS freeglut

But that made me look up the (much) older version, SDL 1.2 which appears to use a 2D framebuffer and mentions several BSDs. So maybe OP would find it useful, either to use or just to read the source code for seeing how BSD framebuffer usage works (worked?). https://github.com/libsdl-org/SDL-1.2

SDL - The older 1.2 version. However this has portability benefits to older platforms (old Linux, Amiga, etc). It is also simpler than SDL2 and as such can be easily "mapped" on-top of other APIs. For example Emscripten provides it inbuilt, mapped over the DOM / Canvas stuff.

SDL has a github, and there's a separate repository for 1.2 with HTML documentation in it: https://github.com/libsdl-org/SDL-1.2/tree/main/docs

I'm guessing you're thinking of the GLUT spec, of which FreeGLUT is an implementation.

If you are going down the glut way, it's freeglut what you should be looking at https://freeglut.sourceforge.net/

I don't expect any of the memory leaks you discovered to originate in freeglut, but if you think there is an issue with it, please report it on our bug tracker on github (https://github.com/FreeGLUTProject/freeglut/issues), with all the relevant information (like this program, and valgrind output, or whatever else is relevant).

an alternative to GLUT is FreeGLUT, but the problem with that is that It's not as useful as GLFW still

FreeGLUT - Modeled after the old GLUT from the early days of OpenGL. Very light; supported by almost all desktop (Win, Mac, Posix) platforms.

Eh, the FreeGLUT folks are keeping the dream(?) alive.