code: function() {
          if (!this.boxOffsets) {
              // Determine the box model. If the testDiv's clientWidth is 3, then
              // the borders are outside and we are dealing with the w3c box
              // model. Otherwise, the browser uses the traditional box model and
              // the borders are inside the box bounds, leaving us with a
              // clientWidth of 1.
              var testDiv = document.createElement("div");
              //testDiv.style.visibility = "hidden";
              testDiv.style.position = "absolute";
              testDiv.style.border = "1px solid black";
              testDiv.style.width = "3px";
              document.body.appendChild(testDiv);
              var w3cBoxModel = testDiv.clientWidth == 3;
              document.body.removeChild(testDiv);
              
              var left = parseInt(OpenLayers.Element.getStyle(this.zoomBox,
                  "border-left-width"));
              var right = parseInt(OpenLayers.Element.getStyle(
                  this.zoomBox, "border-right-width"));
              var top = parseInt(OpenLayers.Element.getStyle(this.zoomBox,
                  "border-top-width"));
              var bottom = parseInt(OpenLayers.Element.getStyle(
                  this.zoomBox, "border-bottom-width"));
              this.boxOffsets = {
                  left: left,
                  right: right,
                  top: top,
                  bottom: bottom,
                  width: w3cBoxModel === false ? left + right : 0,
                  height: w3cBoxModel === false ? top + bottom : 0
              };
          }
          return this.boxOffsets;
      }
docs: Method: getBoxOffsets
  Determines border offsets for a box, according to the box model.
  
  Returns:
  {Object} an object with the following offsets:
  - left
  - right
  - top
  - bottom
  - width
  - height