docs: public boolean removeThisMessageFilter(BaseMessageFilter filter)
      {
          if (m_filter instanceof BaseMessageFilter)
          {
              if (m_filter != filter) // Should be this one.
                  return false;   // Error
              m_filter = null;
              return true;    // Success
          }
          else
              return (((Map)m_filter).remove(filter.getFilterID()) != null);
      }