rem: div.style.zIndex = this.Z_INDEX_BASE['Control'] + this.controls.length; this.viewPortDiv.appendChild( div ); 
add:  if(!div.parentNode) { div.style.zIndex = this.Z_INDEX_BASE['Control'] + this.controls.length; this.viewPortDiv.appendChild( div ); } 
context:     addControlToMap: function (control, px) {        control.setMap(this);        var div = control.draw(px);        if (div) {            div.style.zIndex = this.Z_INDEX_BASE['Control'] +                                this.controls.length;            this.viewPortDiv.appendChild( div );        }    },
meta: 8310	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/8310/46767efed29d3dc02597793dff942a09aba58272/Map.js/buggy/lib/OpenLayers/Map.js