public void handleCreateNotify(XEvent xev) {
   XAnyEvent xany = xev.get_xany();
   if (xany.get_window() != getWindow()) {
     synchronized (getStateLock()) {
       children.add(xany.get_window());
     }
   }
 }
 public void handleDestroyNotify(XEvent xev) {
   XAnyEvent xany = xev.get_xany();
   if (xany.get_window() == getWindow()) {
     XToolkit.removeFromWinMap(getWindow(), this);
     if (XPropertyCache.isCachingSupported()) {
       XPropertyCache.clearCache(getWindow());
     }
   }
   if (xany.get_window() != getWindow()) {
     synchronized (getStateLock()) {
       children.remove(xany.get_window());
     }
   }
 }