function resize() {
	calculatePositions();
}

function setMenuBackground(menuItem) {
	
	if (menuid == null || menuItem != document.getElementById(menuid)) {
		if (menuItem == null) {
			document.getElementById("menuItemBackground").style.display = "none";
		} else {
			var pos = getAbsolutePos(menuItem);
			document.getElementById("menuItemBackground").style.top = "0px";
			document.getElementById("menuItemBackground").style.left = pos.x + "px";
			document.getElementById("menuItemBackground").style.width = parseInt(menuItem.offsetWidth) + "px";
			document.getElementById("menuItemBackground").style.height = "25px";
			document.getElementById("menuItemBackground").style.display = "block";
		}
	}
}

var __isIE = navigator.appVersion.match(/MSIE/);
var __userAgent = navigator.userAgent;
var __isFireFox = __userAgent.match(/firefox/i);
var __isFireFoxOld = __isFireFox && (__userAgent.match(/firefox\/2./i) || __userAgent.match(/firefox\/1./i));
var __isFireFoxNew = __isFireFox && !__isFireFoxOld;


function __parseBorderWidth(width) {
	var res = 0;
	if (typeof (width) == "string" && width != null && width != "") {
		var p = width.indexOf("px");
		if (p >= 0) {
			res = parseInt(width.substring(0, p));
		}
		else {
			//do not know how to calculate other values (such as 0.5em or 0.1cm) correctly now
			//so just set the width to 1 pixel
			res = 1;
		}
	}
	return res;
}


//returns border width for some element
function __getBorderWidth(element) {
	var res = new Object();
	res.left = 0; res.top = 0; res.right = 0; res.bottom = 0;
	if (window.getComputedStyle) {
		//for Firefox
		var elStyle = window.getComputedStyle(element, null);
		res.left = parseInt(elStyle.borderLeftWidth.slice(0, -2));
		res.top = parseInt(elStyle.borderTopWidth.slice(0, -2));
		res.right = parseInt(elStyle.borderRightWidth.slice(0, -2));
		res.bottom = parseInt(elStyle.borderBottomWidth.slice(0, -2));
	}
	else {
		//for other browsers
		res.left = __parseBorderWidth(element.style.borderLeftWidth);
		res.top = __parseBorderWidth(element.style.borderTopWidth);
		res.right = __parseBorderWidth(element.style.borderRightWidth);
		res.bottom = __parseBorderWidth(element.style.borderBottomWidth);
	}

	return res;
}

//returns absolute position of some element within document
function getAbsolutePos(element) {
	var res = new Object();
	res.x = 0; res.y = 0;
	if (element !== null) {
		res.x = element.offsetLeft;
		res.y = element.offsetTop;

		var offsetParent = element.offsetParent;
		var parentNode = element.parentNode;
		var borderWidth = null;

		while (offsetParent != null) {
			res.x += offsetParent.offsetLeft;
			res.y += offsetParent.offsetTop;

			var parentTagName = offsetParent.tagName.toLowerCase();

			if ((__isIE && parentTagName != "table") || (__isFireFoxNew && parentTagName == "td")) {
				borderWidth = __getBorderWidth(offsetParent);
				res.x += borderWidth.left;
				res.y += borderWidth.top;
			}

			if (offsetParent != document.body && offsetParent != document.documentElement) {
				res.x -= offsetParent.scrollLeft;
				res.y -= offsetParent.scrollTop;
			}

			//next lines are necessary to support FireFox problem with offsetParent
			if (!__isIE) {
				while (offsetParent != parentNode && parentNode !== null) {
					res.x -= parentNode.scrollLeft;
					res.y -= parentNode.scrollTop;

					if (__isFireFoxOld) {
						borderWidth = _getBorderWidth(parentNode);
						res.x += borderWidth.left;
						res.y += borderWidth.top;
					}
					parentNode = parentNode.parentNode;
				}
			}

			parentNode = offsetParent.parentNode;
			offsetParent = offsetParent.offsetParent;
		}
	}
	return res;
}


// Script for example event goes here
window.onresize = resize;