private void UpdateSelectedValue()
    {
#if VS2008
      string newValue = String.Join( Delimiter, SelectedItems.Cast<object>().Select( x => GetItemValue( x ).ToString() ).ToArray() );
#else
      string newValue = String.Join( Delimiter, SelectedItems.Cast<object>().Select( x => GetItemValue( x ) ) );
#endif
      if( String.IsNullOrEmpty( SelectedValue ) || !SelectedValue.Equals( newValue ) )
      {
        _ignoreSelectedValueChanged = true;
        SelectedValue = newValue;
        _ignoreSelectedValueChanged = false;
      }
    }