For the other, I know that X11 also has XWarpPointer, no idea about
glutWarpPointer, I don't know any GLUT. If none of the gem devs want it,
you could make yourself a very small external that wouldn't depend on gem
but would just call glutWarpPointer or XWarpPointer. I know that for the
latter, the code wouldn't need to be more than 20 lines.