code: function(width) {
          var me = this,
              isNum = (typeof width == 'number');
  
          if (isNum && me.autoBoxAdjust && !me.isBorderBox()) {
              width -= (me.getBorderWidth("lr") + me.getPadding("lr"));
          }
          return (isNum && width < 0) ? 0 : width;
      }
docs: TODO: Look at this private  ==> used by Fx