/* gcc $(pkg-config --cflags --libs x11 gl) */
#include <stdio.h>
#include <assert.h>
#include <GL/glx.h>

int main (void) {
    int major, minor;
    Display *device;

    device = XOpenDisplay (NULL);
    assert (glXQueryVersion (device, &major, &minor));
    printf ("major: %d minor: %d\n", major, minor);
    XCloseDisplay (device);

    return 0;
}