code: function (xy) {
          this.callback("start", []);
          this.zoomBox = OpenLayers.Util.createDiv('zoomBox', {
              x: -9999, y: -9999
          });
          this.zoomBox.className = this.boxDivClassName;                                         
          this.zoomBox.style.zIndex = this.map.Z_INDEX_BASE["Popup"] - 1;
          
          this.map.viewPortDiv.appendChild(this.zoomBox);
          
          OpenLayers.Element.addClass(
              this.map.viewPortDiv, "olDrawBox"
          );
      }
docs: Method: startBox
  
  Parameters:
  xy - {<OpenLayers.Pixel>}