code: function calculateScrollBarSize(){ //this should happen after the floating table has been positioned
          if($scrollContainer.length){
            if(opts.support && opts.support.perfectScrollbar && $scrollContainer.data().perfectScrollbar){
              scrollbarOffset = {horizontal:0, vertical:0};
            } else {
              if($scrollContainer.css('overflow-x') == 'scroll'){
                scrollbarOffset.horizontal = scrollbarWidth;
              } else {
                var sw = $scrollContainer.width(), tw = tableWidth($table, $fthCells);
                var offsetv = sh < th ? scrollbarWidth : 0;
                scrollbarOffset.horizontal = sw - offsetv < tw ? scrollbarWidth : 0;
              }
              if($scrollContainer.css('overflow-y') == 'scroll'){
                scrollbarOffset.vertical = scrollbarWidth;
              } else {
                var sh = $scrollContainer.height(), th = $table.height();
                var offseth = sw < tw ? scrollbarWidth : 0;
                scrollbarOffset.vertical = sh - offseth < th ? scrollbarWidth : 0;
              }
            }
          }
        }
docs: checks if THIS table has scrollbars, and finds their widths