code: function (p_oOverlay) {
  
              var oOverlay = this.find(p_oOverlay),
                  nTopZIndex,
                  oTopOverlay,
                  aOverlays;
  
              if (oOverlay) {
  
                  aOverlays = this.overlays;
                  aOverlays.sort(this.compareZIndexDesc);
  
                  oTopOverlay = aOverlays[0];
  
                  if (oTopOverlay) {
                      nTopZIndex = Dom.getStyle(oTopOverlay.element, "zIndex");
  
                      if (!isNaN(nTopZIndex)) {
  
                          var bRequiresBump = false;
  
                          if (oTopOverlay !== oOverlay) {
                              bRequiresBump = true;
                          } else if (aOverlays.length > 1) {
                              var nNextZIndex = Dom.getStyle(aOverlays[1].element, "zIndex");
                              // Don't rely on DOM order to stack if 2 overlays are at the same zindex.
                              if (!isNaN(nNextZIndex) && (nTopZIndex == nNextZIndex)) {
                                  bRequiresBump = true;
                              }
                          }
  
                          if (bRequiresBump) {
                              oOverlay.cfg.setProperty("zindex", (parseInt(nTopZIndex, 10) + 2));
                          }
                      }
                      aOverlays.sort(this.compareZIndexDesc);
                  }
              }
          }
docs: Places the specified Overlay instance on top of all other
  Overlay instances.
  @method bringToTop
  @param {YAHOO.widget.Overlay} p_oOverlay Object representing an
  Overlay instance.
  @param {String} p_oOverlay String representing the id of an
  Overlay instance.