var isIE = /msie/i.test(navigator.userAgent) && !/opera/i.test(navigator.userAgent);
var afbeeldingen_map = "afbeeldingen";
var numCategories = 4;
var cat = 0;

function get(id)
{
	return document.getElementById(id);
}

function addEvent(node, eventName, handler)
{
	isIE ? node.attachEvent("on" + eventName, handler) : node.addEventListener(eventName, handler, false);
}

function createMouseoverHandler(k, bool)
{
	return function () {mouseoverHandler(k, bool);};
}

function mouseoverHandler(k, bool)
{
	if (cat > 0 && cat != k)
	{
		highlightSubmenuItem(cat, !bool)
	}
	if (cat != k)
	{
		highlightSubmenuItem(k, bool);
	}
}

function highlightSubmenuItem(k, bool)
{
	var menuItem = get("submenu" + k);
	var spans = menuItem.getElementsByTagName("span");
	spans[0].style.display = (bool) ? "block" : "none";
	spans[1].style.backgroundPosition = bool ? "right" : "left";	
	if (get("sec_submenu"))
	{
		menuItem = get("sec_submenu" + k);
		var spans = menuItem.getElementsByTagName("span");
		spans[0].style.textDecoration = bool ? "underline" : "none";
	}
}

function init()
{
	for (var k = 1; k <= numCategories; k++)
	{
		var anchors = get("submenu" + k).getElementsByTagName("a");
		var submenuItem = anchors[0];
		addEvent(submenuItem, "mouseover", createMouseoverHandler(k, true)); 
		addEvent(submenuItem, "mouseout", createMouseoverHandler(k, false));  
	}
}

addEvent(window, "load", init);