How long, in seconds, has XWindows been idle

idletime.c

// gcc -Wall idletime.c -o idletime -L/usr/X11R6/lib/ -lX11 -lXext -lXss

#include <stdio.h>
#include <X11/extensions/scrnsaver.h>

int main()
{
	XScreenSaverInfo *info = XScreenSaverAllocInfo();
	Display *display = XOpenDisplay (NULL);
	if (display == NULL) {
		return 1;
	}
	int screen = DefaultScreen (display);
	XScreenSaverQueryInfo (display, RootWindow (display, screen), info);

        printf ("%ld\n", info->idle / 1000);

	XFree (info);
	XCloseDisplay (display); 
        return 0;
}