private void OnMasterColumnFittedWidthRequested(object sender, FittedWidthRequestedEventArgs e)
            {
                Debug.Assert(( ColumnBase )sender == this.MasterColumn);

                var fittedWidth = this.DetailColumn.GetFittedWidth();

                if (fittedWidth < 0d)
                {
                    return;
                }

                e.SetValue(fittedWidth);
            }
      private void OnMasterColumnFittedWidthRequested( object sender, FittedWidthRequestedEventArgs e )
      {
        Debug.Assert( ( ColumnBase )sender == this.MasterColumn );

        var fittedWidth = this.DetailColumn.GetFittedWidth();
        if( fittedWidth < 0d )
          return;

        e.SetValue( fittedWidth );
      }