Aiuto per rendere compatibile uno script (fade in/out) con Opera

[superpelo]

Ciao a tutti,
come da titolo ho realizzato (prendendo spunto qua e là ) uno script per il fade in/out di immagini che funziona bene su FF e IE. Il problema nasce però con Opera, pare essere totalmente incompatibile con tale browser.

Potete darmi una mano?

var browserdetect = null;
var opacity = null;
var timerID = new Array();
var listaBottoni = new Array();
var delay = 75;

function increaseOpacity(image){
	obj = image;
	clearTimer(obj.src);
	setOpacity(obj,0);
	timerID[obj.src] = setInterval("fade(obj,1)",delay);
}

function decreaseOpacity(image){
	obj = image;
	clearTimer(obj.src);
	setOpacity(obj,opacity);
	timerID[obj.src] = setInterval("fade(obj,0)",delay);
}

function setOpacity(obj,value) {
	if ( browserdetect == "mozilla" )
		obj.style.MozOpacity = value/100;
	else if ( browserdetect == "ie" ) {
		obj.style.cssText = "filter:alpha(opacity="+opacity+");";
		obj.filters[0].opacity = value;
	}
}

function clearTimer(_index){
	for (i = 0; i < listaBottoni.length; i++) {
		if ( listaBottoni[i].src != _index )
			setOpacity(listaBottoni[i],opacity);
	}
	for ( var index in timerID ) {
		if ( timerID[index] )
			clearInterval(timerID[index]);
	}

}

function fade(obj,in_out){
	if ( in_out == 1 ) {
		if ( browserdetect == "mozilla" && obj.style.MozOpacity < 1 )
			obj.style.MozOpacity = Math.min(parseFloat(obj.style.MozOpacity)+0.1, (opacity/100) );
		else if ( browserdetect == "ie" && obj.filters[0].opacity < opacity ) {
			obj.filters[0].opacity += 10;
		}
		else
			clearTimer(obj.src);
	}
	else {
		if ( browserdetect == "mozilla" && obj.style.MozOpacity > 0 )
			obj.style.MozOpacity = Math.max(parseFloat(obj.style.MozOpacity)-0.1, 0.00);
		else if ( browserdetect == "ie" && obj.filters[0].opacity > 0 ) {
			obj.filters[0].opacity -= 10;
		}
		else
			clearTimer(obj.src);
	}
}

window.onload = function() {
	opacity = 55;
	node = document.getElementsByTagName('body');
	listaBottoni = getElementsByClass('bottone',node[0],'img');
	if ( listaBottoni.length > 0 )
		browserdetect = ( listaBottoni[0].filters ) ? "ie" : ( typeof listaBottoni[0].style.MozOpacity == "string" ) ? "mozilla" : "";
	for (i = 0; i < listaBottoni.length; i++) {
		listaBottoni[i].src = 'b_1'+(i)+'.gif';
		setOpacity(listaBottoni[i],opacity);
	}
}

function getElementsByClass(searchClass,node,tag) {
	var classElements = new Array();
	if ( node == null )
		node = document;
	if ( tag == null )
		tag = '*';
	var els = node.getElementsByTagName(tag);
	var elsLen = els.length;
	var pattern = new RegExp("(^|\\s)"+searchClass+"(\\s|$)");
	for (i = 0, j = 0; i < elsLen; i++) {
		if ( pattern.test(els[i].className) ) {
			classElements[j] = els[i];
			j++;
		}
	}
	return classElements;
}

Grazie in aticipo.