public void setSubscribed(String newsgroup, boolean flag)
  {
    if (subs == null)
      {
        load();
      }
    if (flag && !groups.contains(newsgroup))
      {
        groups.add(newsgroup);
      }
    boolean subscribed = subs.contains(newsgroup);
    if (flag && !subscribed)
      {
        subs.add(newsgroup);
        dirty = true;
      }
    else if (!flag && subscribed)
      {
        subs.remove(newsgroup);
        dirty = true;
      }
  }