Miscellany

void main(){
 int screen_num;
 xcb_connection_t* conn = xcb_connect(null, &screen_num);
         /* Get the preferred screen. */
 xcb_screen_iterator_t screen_iter = xcb_setup_roots_iterator(xcb_get_setup(conn));
 while(screen_num--)
         xcb_screen_next(&screen_iter);
 xcb_screen_t* screen = screen_iter.data;
 
 xcb_get_geometry_reply_t* attr = xcb_get_geometry_reply(conn, xcb_get_geometry(conn, screen.root), null);
}