Xlib: получение списка окон и их имен

#include <stdio.h>
#include <X11/Xlib.h>
#include <X11/Xatom.h>
#include <assert.h>
static void* x11property(Display *dpy, Window win, Atom prop, Atom type, int *nitems) {
   Atom type_ret;
   int format_ret;
   unsigned long items_ret;
   unsigned long after_ret;
   unsigned char *prop_data = 0;
   if (XGetWindowProperty(dpy, win, prop, 0, 0x7fffffff, False, type,
         &type_ret, &format_ret, &items_ret, &after_ret, &prop_data) != Success)
      return 0;
   if (nitems)
      *nitems = items_ret;
   return prop_data;
}
int main() {
    Atom atom_client_list;
    Atom atom_netwmname;
    Atom atom_utf8;
    Display *dpy;
    Window root, *winlist, activewin;
    int num;
    dpy = XOpenDisplay(NULL);
    assert(dpy != NULL);
    root = DefaultRootWindow(dpy);
    atom_client_list = XInternAtom(dpy, "_NET_CLIENT_LIST", False);
    atom_netwmname = XInternAtom(dpy, "_NET_WM_NAME", False);
    atom_utf8 = XInternAtom(dpy, "UTF8_STRING", False);
    winlist = (Window*)x11property(dpy, root, atom_client_list, XA_WINDOW, &num);
    if (winlist) {
        int i;
        for (i = 0; i < num; ++i) {
            /*
            char *name = NULL;
            XFetchName(dpy, winlist[i], &name);
            printf("%c %#lx %s\n", winlist[i] == activewin ? '*' : ' ', (unsigned long) winlist[i], name);
            XFree(name);*/
            unsigned char *name = NULL;
            name = (unsigned char *)x11property(dpy, winlist[i], atom_netwmname, atom_utf8, NULL);
            printf("name == NULL - %s\n", name == NULL ? "True" : "False");
            printf("%s\n", name);
            XFree(name);
        }
        XFree(winlist);
    }
    XCloseDisplay(dpy);
    return 0;
}