Table info doesn't take x scrollbar into account about scroller HOT 1 OPEN

var _my_fnMeasure = function(Redraw){
  if ( this.s.autoHeight )
  {
    this._fnCalcRowHeight();
  }

  var heights = this.s.heights;
  /////below, the only line that changes
  heights.viewport = this.dom.scroller.clientHeight || $(this.dom.scroller).height();
  this.s.viewportRows = parseInt( heights.viewport / heights.row, 10 )+1;
  this.s.dt._iDisplayLength = this.s.viewportRows * this.s.displayBuffer;

  if ( bRedraw === undefined || bRedraw )
  {
    this.s.dt.oInstance.fnDraw();
  }
},

$table.dataTable({
        ....
    }).on('init.dt', function ( e, settings, json ) {
        settings.oScroller.fnMeasure = _my_fnMeasure;
        settings.oScroller.fnMeasure();
    });

});