private void SetResortCallback(SortDescriptionCollection sortDescriptions, ColumnCollection columns)
        {
            var collection = sortDescriptions as DataGridSortDescriptionCollection;

            if ((m_resortCallback != null) || (collection == null) || !collection.IsResortDefered)
            {
                return;
            }

            m_resortCallback = new ResortCallback(this, sortDescriptions, columns);
            collection.AddResortNotification(m_resortCallback);
        }
    private void SetResortCallback( SortDescriptionCollection sortDescriptions, ColumnCollection columns )
    {
      var collection = sortDescriptions as DataGridSortDescriptionCollection;
      if( ( m_resortCallback != null ) || ( collection == null ) || !collection.IsResortDefered )
        return;

      m_resortCallback = new ResortCallback( this, sortDescriptions, columns );
      collection.AddResortNotification( m_resortCallback );
    }