    : '', // add "bootstrap-icon-white" to make them white; this icon class is added to the <i> in the header
      iconSortNone : 'bootstrap-icon-unsorted', // class name added to icon when column is not sorted
      iconSortAsc  : 'glyphicon glyphicon-chevron-up', // class name added to icon when column has ascending sort
      iconSortDesc : 'glyphicon glyphicon-chevron-down', // class name added to icon when column has descending sort
      filterRow    : '', // filter row class; use widgetOptions.filte