code: function() {
        inputEx.UrlField.superclass.render.call(this);
        this.el.size = this.options.size;
  
        if(!this.options.favicon) {
           YAHOO.util.Dom.addClass(this.el, 'nofavicon');
        }
  
        // Create the favicon image tag
        if(this.options.favicon) {
           this.favicon = inputEx.cn('img', {src: inputEx.spacerUrl});
           this.fieldContainer.insertBefore(this.favicon,this.fieldContainer.childNodes[0]);
  
           // focus field when clicking on favicon
           YAHOO.util.Event.addListener(this.favicon,"click",function(){this.focus();},this,true);
        }
     }
docs: Adds a img tag before the field to display the favicon