/*
 * gcc -o subwindow-field $(pkg-config --cflags --libs x11) subwindow-field.c
 */

#include <stdio.h>
#include <stdarg.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xutil.h>

int main(int argc, char **argv)
{
	Display             *dpy;
	Screen              *scr;
	Window               win, subwin;
	XEvent               ev;
	unsigned long        pixel;

	dpy = XOpenDisplay(NULL);
	if (dpy == NULL) {
		fprintf (stderr, "Failed to open display\n");
		exit (1);
	}
	scr = DefaultScreenOfDisplay (dpy);
	pixel = BlackPixel (dpy, DefaultScreen (dpy));

        win = XCreateSimpleWindow(dpy, DefaultRootWindow(dpy), 0, 0, 500, 500, 0, pixel, pixel);
        subwin = XCreateSimpleWindow(dpy, win, 0, 0, 500, 500, 0, pixel, pixel);

        XSelectInput(dpy, win, ButtonPressMask|ButtonReleaseMask);

        XMapWindow(dpy, subwin);
        XMapWindow(dpy, win);

	while (1) {
		XNextEvent(dpy, &ev);

		if (ev.type == ButtonPress) {
			XButtonEvent *bev = (XButtonEvent *) &ev;

			fprintf (stdout, "ButtonPress %i received in window 0x%lx, subwindow 0x%lx\n",
			         bev->button,
			         bev->window,
			         bev->subwindow);

			if (bev->subwindow == subwin)
				fprintf (stdout, "*** SUCCESS *** Subwindow is set\n");
			else
				fprintf (stderr, "*** FAILURE *** Subwindow is not set\n");

		}
	}

	return 0;
}