static <A> CloseableIterableIterator<A> iterate_progressWindow(final Collection<A> l) {
  final JProgressBar bar = showProgressWindow(l(l));
  ret iteratorFromFunction_withEndMarker_f0_autoCloseable(new F0 {
    int i;
    Iterator<A> it = iterator(l);
    NotTooOften nto = onlyTenTimesASecond();
    
    public O get() {
      if (!it.hasNext()) ret endMarker();
      if (i > 0 && nto.yo()) {
        setProgressBarValue(bar, i);
        // TODO: set window title too
      }
      ++i;
      ret it.next();
    }
  }, tempDisposePIFrame(bar));
}