#include <X11/Xlib.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void *getproperty (Display *display, Window win, Atom at, Atom type, int *num_results) {

	Atom type_ret;
	int format = 0;
	unsigned long nitems;
	unsigned long items = 0;
	unsigned long bytes = 0;
	unsigned char **prop_value;
	int result;

	result = XGetWindowProperty(display, win, at, 0, 0x7fffffff, False, type, &type_ret, &format, &nitems, &bytes, (unsigned char **)&prop_value);

	if (result != 0) {
		printf ("result from XGetWindowProperty not 0, %d instead!\n", result);
	}

	*num_results = nitems;

	return prop_value;

}

char *getwindowname(Display *display, Window window) {

	char *windowname;
	int items;

	windowname = getproperty(display, window, XInternAtom(display, "WM_ICON_NAME", True), AnyPropertyType, &items);

	return (char *)(windowname ? windowname : "Unnamed Window");

}

unsigned char **getwindowlist(Display *display, int *clientcount) {

	int i;
	unsigned char **clientlist;

	clientlist = getproperty(display, RootWindow(display, 0), XInternAtom(display, "_NET_CLIENT_LIST", True), AnyPropertyType, clientcount);

	return clientlist;

}

int main(void) {

	Display *display;
	Window window;
	XEvent event;
	int clientcount,i = 0;
	unsigned char **clientlist;

	if( !(display = XOpenDisplay(NULL)) ){
		fprintf(stderr, "Cannot open display\n");
		exit(1);
	}

	clientlist = getwindowlist(display, (int *)&clientcount);

	for (i = 0; i < clientcount; i++) {

		XSelectInput (display, (int)clientlist[i], StructureNotifyMask | FocusChangeMask | VisibilityChangeMask);

		printf("%u: %s\n", clientlist[i], getwindowname(display, (int)clientlist[i]));

	}

	return 0;

}