gistfile1.txt

#include <stdio.h>
#include <X11/Xlib.h>
#include <X11/extensions/XInput2.h>

int main() {

  /* Connect to the X server */
	Display *dpy = XOpenDisplay(NULL);

	/* XInput Extension available? */
	int opcode, event, error;
	if (!XQueryExtension(dpy, "XInputExtension", &opcode, &event, &error)) {
		printf("X Input extension not available.\n");
		return -1;
	}

	/* Which version of XI2? We support 2.0 */
	int major = 2, minor = 0;
	if (XIQueryVersion(dpy, &major, &minor) == BadRequest) {
		printf("XI2 not available. Server supports %d.%d\n", major, minor);
		return -1;
	}
}