protected void setupEvents(MultiSelectPopup popup_, bool do_)
    {
      if (popup_ == null)
        return;

      popup_.Closed -= new EventHandler(popupClosed);

      if (do_)
        popup_.Closed += new EventHandler(popupClosed);
    }
    protected void showPopup()
    {
      MultiSelectPopup popup;
      Point p;

      if (m_coll==null || m_coll.Count == 0)
        return;

      popup = new MultiSelectPopup(m_coll, m_singleSelect);
      p = PointToScreen(new Point(0, 0));
      popup.Location = new Point(p.X, p.Y + Height);
      setupEvents(popup, true);
      popup.Show();
    }