var imagesCached = false
var imagePath = root + "images/gui/"
var cachedImages = []
var dynImages = []

dynImages['arrow'] = ['sidenav_arrow_up.gif', 'sidenav_arrow_over.gif']
dynImages['aboutBtn'] = ['about_up.gif', 'about_over.gif']
dynImages['contactBtn'] = ['contact_up.gif', 'contact_over.gif']
dynImages['registrationBtn'] = ['registration_up.gif', 'registration_over.gif']
dynImages['speakersBtn'] = ['speakers_up.gif', 'speakers_over.gif']

function leftNavOver(imgName) {
	var img, rollSrc
	if (document.images && imagesCached) {
		img = document.images[imgName]
		rollSrc = cachedImages['arrow'][1].src
		img.src = rollSrc
	}
	return true
}

function leftNavOut(imgName) {
	var img, defaultSrc
	if (document.images && imagesCached) {
		img = document.images[imgName]
		defaultSrc = cachedImages['arrow'][0].src
		img.src = defaultSrc
	}
	return true
}

function roll_over(imgName) {
	var img, rollSrc
	if (document.images && imagesCached) {
		img = document.images[imgName]
		rollSrc = cachedImages[imgName][1].src
		img.src = rollSrc
	}
	return true
}

function roll_out(imgName) {
	var img, defaultSrc
	if (document.images && imagesCached) {
		img = document.images[imgName]
		defaultSrc = cachedImages[imgName][0].src
		img.src = defaultSrc
	}
	return true
}
function preloadImages() {
	if (document.images) {
		for (var imgName in dynImages) {
			cachedImages[imgName] = new Array()
			for (var i = 0; i < dynImages[imgName].length; i++) {
				cachedImages[imgName][i] = new Image
				cachedImages[imgName][i].src = imagePath + dynImages[imgName][i]
			}
		}	
	}
	return true
}
		
function NS_flattenImages (documentObj) {
	if (document.layers) {
		var me = NS_flattenImages
		if (!documentObj) {
			documentObj = window.document
		}
		for (var i = 0; i < documentObj.images.length; i++) {
			var img = documentObj.images[i]
			if (img.name && !document.images[img.name]) {
				document.images[img.name] = img
			}
		}
		for (var i = 0; i <  documentObj.layers.length; i++) {
			me(documentObj.layers[i].document)
		}
	}
	return true
}

function initPage () {
	window.isLoaded = true
	imagesCached = preloadImages()
	if ( document.layers && (document.layers.length > 0) )
		NS_flattenImages();
	setMenuEvtHandlers()
}

window.onload = initPage