var DropDownMenu = Class.create();

DropDownMenu.prototype = {
	initialize: function(menuElement) {
		menuElement.childElements().each(function(node){
			var submenu = $A(node.getElementsByTagName("ul")).first();
			if(submenu != null){
				Element.extend(submenu).setStyle({display: 'none'});
				node.onmouseover = node.onmouseout = function(){
					Element.toggle(submenu);
					node.toggleClassName('hovering');
				}
			}
		});
	}
};

function correctPNG() { // correctly handle PNG transparency in Win IE 5.5 & 6
    var arVersion = navigator.appVersion.split("MSIE")
    var version = parseFloat(arVersion[1])
    if ((version >= 5.5) && (document.body.filters)) 
    {
	for(var i=0; i<document.images.length; i++)
	{
	    var img = document.images[i];
	    var imgName = img.src.toUpperCase()
	    if (imgName.substring(imgName.length-3, imgName.length) == "PNG")
	    {
		var imgID = (img.id) ? "id='" + img.id + "' " : ""
		var imgClass = (img.className) ? "class='" + img.className + "' " : ""
		var imgTitle = (img.title) ? "title='" + img.title + "' " : "title='" + img.alt + "' "
		var imgStyle = "display:inline-block;" + img.style.cssText 
		if (img.align == "left") imgStyle = "float:left;" + imgStyle
		if (img.align == "right") imgStyle = "float:right;" + imgStyle
		if (img.parentElement.href) imgStyle = "cursor:hand;" + imgStyle
		var strNewHTML = "<span " + imgID + imgClass + imgTitle
		    + " style=\"" + "width:" + img.width + "px; height:" + img.height + "px;" + imgStyle + ";"
		    + "filter:progid:DXImageTransform.Microsoft.AlphaImageLoader"
		    + "(src=\'" + img.src + "\', sizingMethod='scale');\"></span>" 
		img.outerHTML = strNewHTML
		i = i-1
	    }
	}
    }    
}

document.observe('dom:loaded', function() {
	var menu = new DropDownMenu($('topnav').down('ul'));
});