/**
   * Returns the WhiteboardFrame associated with the Contact.
   *
   * @param c contact
   * @return WhiteboardFrame with the Contact or null (if nothing found)
   */
  private WhiteboardFrame getWhiteboardFrame(WhiteboardSession session) {
    WhiteboardFrame whiteboardFrame = null;

    for (int i = 0; i < wbFrames.size(); i++) {
      whiteboardFrame = (WhiteboardFrame) wbFrames.get(i);

      if (whiteboardFrame.getWhiteboardSession().equals(session)) return whiteboardFrame;
    }
    return null;
  }