docs: function(id, img, xy, sz) {
          var imgLocation = OpenLayers.Util.getImageLocation(img);
          var btn = OpenLayers.Util.createAlphaImageDiv(
                                      this.id + "_" + id, 
                                      xy, sz, imgLocation, "absolute");
          btn.style.cursor = "pointer";
          //we want to add the outer div
          this.div.appendChild(btn);
          btn.action = id;
          btn.className = "olButton";
      
          //we want to remember/reference the outer div
          this.buttons.push(btn);
          return btn;
      }