const char *glxExts = glXQueryExtensionsString(s_Display, s_XVisualInfo->screen);
  PFNGLXSWAPINTERVALEXTPROC glXSwapIntervalEXT = NULL;

  if (glxExts && strstr(glxExts, "GLX_EXT_swap_control")) {
      // get function pointer
      glXSwapIntervalEXT = (PFNGLXSWAPINTERVALEXTPROC)
          glXGetProcAddress((const GLubyte *)"glXSwapIntervalEXT");
  }

  if (glXSwapIntervalEXT) {
      // Set swap interval to 0 -> disable VSync (uncapped FPS)
      glXSwapIntervalEXT(s_Display, win, 0);
      printf("GLX_EXT_swap_control available - swap interval set to 0\n");
  } else {
      printf("GLX_EXT_swap_control not available; cannot set swap interval via glXSwapIntervalEXT\n");
      printf("If you have GLX_MESA_swap_control or GLX_SGI_swap_control, use appropriate function.\n");
  }