code: public boolean close() {
          List t = (List)((ArrayList)windows).clone();
          Iterator e = t.iterator();
          while (e.hasNext()) {
              ApplicationWindow window = (ApplicationWindow)e.next();
              if (!window.close()) { return false; }
          }
          if (subManagers != null) {
              e = subManagers.iterator();
              while (e.hasNext()) {
                  WindowManager wm = (WindowManager)e.next();
                  if (!wm.close()) { return false; }
              }
          }
          return true;
      }
docs: Attempts to close all windows managed by this window manager, as well as
  windows managed by any descendent window managers.
  
  @return <code>true</code> if all windows were sucessfully closed, and
  <code>false</code> if any window refused to close