I'm running the following javascript with no problem in FireFox:


Code:
var multiGallery = {
	init: function(options){
		this.overlay = new Element('div').setProperty('id','lbOverlay').injectInside(document.body).addEvent('click',this.close.bind(this));
		this.gallery = new Element('div').setProperty('id','gallery').injectInside(document.body);
		this.fx = {
			overlay: this.overlay.effect('opacity',
...