code: function (element, which) {
                  var style = element.currentStyle;
                  var isIE7 = ariaCoreBrowser.isIE7;
                  var propName = "border" + which + "Width";
  
                  var hasBorder = (style["border" + which + "Style"] != "none");
                  if (!hasBorder) {
                      return 0;
                  }
  
                  var border = style[propName];
                  if (border == "thin") {
                      border = isIE7 ? 2 : 1;
                  } else if (border == "medium") {
                      border = isIE7 ? 4 : 3;
                  } else if (border == "thick") {
                      border = isIE7 ? 6 : 5;
                  }
  
                  // if unitless, will be treated as pixels
                  return this.convertToPixels(String(border), element, propName);
              }
docs: Helper function needed for IE to calculate border size in pixels, since <code>element.currentStyle</code>
  may return non-numeric or non-pixel values for borders.
  @param {HTMLElement} element The DOM element on which to retrieve a CSS property
  @param {String} which either "Left", "Right", "Top" or "Bottom" (case is important)
  @return {Number} border width in pixels