function highlightImage(imgId, doHighlight)
{
	document.getElementById(imgId).style.opacity = doHighlight ? 1 : .7;
	document.getElementById(imgId).style.filter = "alpha(opacity:" + (doHighlight ? 100 : 70) + ")";
}

function init()
{
	this.getFilePart_front = function(src) { return src.substring(0, src.lastIndexOf("_")+1); };
	this.getFilePart_back = function(src) { return src.substring(src.lastIndexOf("."), src.length); };
	var imageCache = new Array();
	
	/* image thumbs
	*  Images default to being faded and are rendered at full opacity when hovered over
	
	var imgObjs = getElementsByClass("thumb_img", document, "img");
	for(var i=0; i<imgObjs.length; i++)
	{
		imgObjs[i].onmouseover = function() { if(typeof(highlightImage) == "function") highlightImage(this.id, true); };
		imgObjs[i].onmouseout = function() { if(typeof(highlightImage) == "function") highlightImage(this.id, false); };
		highlightImage(imgObjs[i].id, false);
	}
	*/
	/* button images
	*
	*/
	var imgObjs = getElementsByClass("button", document, "img");
	imgObjs = imgObjs.concat(getElementsByClass("rollover", document, "img"));
	for(var i=0; i<imgObjs.length; i++)
	{
		imgObjs[i].newSrc_front = getFilePart_front(imgObjs[i].src);
		imgObjs[i].newSrc_back =  getFilePart_back(imgObjs[i].src);
		
		// load images in cache
		imageCache[imageCache.length] = new Image();
		imageCache[imageCache.length-1].src = imgObjs[i].newSrc_front + "on" + imgObjs[i].newSrc_back;
		imageCache[imageCache.length] = new Image();
		imageCache[imageCache.length-1].src = imgObjs[i].newSrc_front + "off" + imgObjs[i].newSrc_back;
		imageCache[imageCache.length] = new Image();
		imageCache[imageCache.length-1].src = imgObjs[i].newSrc_front + "pressed" + imgObjs[i].newSrc_back;
		
		imgObjs.mouseOver = false;
		imgObjs[i].onmouseover = function() 
		{ 
			this.mouseOver = true;
			this.src = this.newSrc_front + "on" + this.newSrc_back;
		};
		imgObjs[i].onmouseout = function() 
		{ 
			this.mouseOver = false;
			this.src = this.newSrc_front + "off" + this.newSrc_back;
		};
		if(imgObjs[i].className.indexOf("button") >= 0)
		{
			imgObjs[i].onmousedown = function()
			{ 
				this.src = this.newSrc_front + "pressed" + this.newSrc_back;
			};
			imgObjs[i].onmouseup = function()
			{
				this.src = this.newSrc_front + (this.mouseOver ? "on" : "off") + this.newSrc_back;
			}
		}
	}
	var test = "hi";
}