-int main(int argc, char **argv)
+#include <glib.h>
+#include <stdio.h>
+#include <string.h>
+#include <xcb/xcb.h>
+
+#define _(a) (a)
+
+/* inherits from xcb_screen_t */
+typedef struct {
+ xcb_screen_t super;
+ int num;
+ xcb_window_t selwin; /* for the selection */
+} d_screen_t;
+
+static xcb_connection_t *conn;
+static const xcb_setup_t *setup;
+static d_screen_t *screens = NULL;
+
+static gboolean
+register_screen (d_screen_t *sc)
{
+ char *name;
+ int len, s;
+ xcb_window_t w;
+ xcb_intern_atom_cookie_t ack;
+ xcb_intern_atom_reply_t *arep;
+ xcb_get_selection_owner_cookie_t sck;
+ xcb_get_selection_owner_reply_t *srep;
+ gboolean taken;
+
+ w = xcb_generate_id(conn);
+ xcb_create_window(conn, XCB_COPY_FROM_PARENT, w, sc->super.root,
+ 0, 0, 1, 1, 0, XCB_WINDOW_CLASS_INPUT_ONLY,
+ sc->super.root_visual, 0, NULL);
+
+ name = g_strdup_printf("_NET_WM_CM_S%d", sc->num);
+ ack = xcb_intern_atom(conn, FALSE, strlen(name), name);
+ arep = xcb_intern_atom_reply(conn, ack, NULL);
+ g_free(name);
+
+ sck = xcb_get_selection_owner(conn, arep->atom);
+ srep = xcb_get_selection_owner_reply(conn, sck, NULL);
+ taken = !!srep->owner;
+ free(srep);
+ if (taken) {
+ printf(_("screen %d already has a composite manager, skipping\n"),
+ sc->num);
+ return FALSE;
+ }
+
+ xcb_set_selection_owner(conn, w, arep->atom, XCB_CURRENT_TIME);
+ sck = xcb_get_selection_owner(conn, arep->atom);
+ srep = xcb_get_selection_owner_reply(conn, sck, NULL);
+ taken = srep->owner == w;
+ if (taken) {
+ sc->selwin = w;
+ return TRUE;
+ }
+ else {
+ xcb_destroy_window(conn, w);
+ return FALSE;
+ }
+}
+
+static gint
+all_screens()
+{
+ xcb_screen_iterator_t it;
+ int count, i;
+ d_screen_t sc;
+
+ count = i = 0;
+ for (it = xcb_setup_roots_iterator(setup); it.rem; xcb_screen_next(&it)) {
+ sc.super = *it.data;
+ sc.num = i++;
+ if (register_screen(&sc)) {
+ ++count;
+ screens = g_renew(d_screen_t, screens, count);
+ screens[count-1] = sc;
+ printf(_("managing screen %d\n"), sc.num);
+ }
+ }
+ return count;
+}
+
+int
+main(int argc, char **argv)
+{
+ conn = xcb_connect(NULL, NULL);
+ if (!conn) {
+ printf(_("Unable to connect to display\n"));
+ return 1;
+ }
+ setup = xcb_get_setup(conn);
+
+ all_screens();
+
+
+ xcb_disconnect(conn);
+ return 0;
}