var isDOM = (document.getElementById ? true : false); 
var isIE4 = ((document.all && !isDOM) ? true : false);
var isNS4 = (document.layers ? true : false);

function getRef(id) {
	if (isDOM) return document.getElementById(id);
	if (isIE4) return document.all[id];
	if (isNS4) return document.layers[id];
}

function getSty(id) {
	return (isNS4 ? getRef(id) : getRef(id).style);
} 

// Hide timeout.
var popTimer = 0;
// Array showing highlighted menu items.
var litNow = new Array();

function popOver(menuNum, itemNum) {
	clearTimeout(popTimer);
	hideAllBut(menuNum);
	litNow = getTree(menuNum, itemNum);
	changeCol(litNow, true);
	targetNum = menu[menuNum][itemNum].target;
	if (targetNum > 0) {
		thisX = parseInt(menu[menuNum][0].ref.left) + parseInt(menu[menuNum][itemNum].ref.left);
		thisY = parseInt(menu[menuNum][0].ref.top) + parseInt(menu[menuNum][itemNum].ref.top);
		with (menu[targetNum][0].ref) {
			left = parseInt(thisX + menu[targetNum][0].x);
			top = parseInt(thisY + menu[targetNum][0].y);
			visibility = 'visible';
	    }
    }
}

function popOut(menuNum, itemNum) {
	if ((menuNum == 0) && !menu[menuNum][itemNum].target)
		hideAllBut(0)
	else
		popTimer = setTimeout('hideAllBut(0)', 500);
}

function getTree(menuNum, itemNum) {

	// Array index is the menu number. The contents are null (if that menu is not a parent)
	// or the item number in that menu that is an ancestor (to light it up).
	itemArray = new Array(menu.length);
	
	while(1) {
		itemArray[menuNum] = itemNum;
		// If we've reached the top of the hierarchy, return.
		if (menuNum == 0) return itemArray;
		itemNum = menu[menuNum][0].parentItem;
		menuNum = menu[menuNum][0].parentMenu;
    }
}

// Pass an array and a boolean to specify colour change, true = over colour.
function changeCol(changeArray, isOver) {
	for (menuCount = 0; menuCount < changeArray.length; menuCount++) {
		if (changeArray[menuCount]) {
			newCol = isOver ? menu[menuCount][0].overCol : menu[menuCount][0].backCol;
			// Change the colours of the div/layer background.
			with (menu[menuCount][changeArray[menuCount]].ref) {
				if (isNS4) bgColor = newCol;
				else backgroundColor = newCol;
		    }
	    }
   }
}

function hideAllBut(menuNum) {
	var keepMenus = getTree(menuNum, 1);
	for (count = 0; count < menu.length; count++) {
		if (!keepMenus[count])
		menu[count][0].ref.visibility = 'hidden';
		changeCol(litNow, false);
	}
}

// *** MENU CONSTRUCTION FUNCTIONS ***

function Menu(isVert, popInd, x, y, width, overCol, backCol, borderClass, textClass) {
	// True or false - a vertical menu?
	this.isVert = isVert;
	// The popout indicator used (if any) for this menu.
	this.popInd = popInd
	// Position and size settings.
	this.x = x;
	this.y = y;
	this.width = width;
	// Colours of menu and items.
	this.overCol = overCol;
	this.backCol = backCol;
	// The stylesheet class used for item borders and the text within items.
	this.borderClass = borderClass;
	this.textClass = textClass;
	// Parent menu and item numbers, indexed later.
	this.parentMenu = null;
	this.parentItem = null;
	// Reference to the object's style properties (set later).
	this.ref = null;
}

function Item(text, href, frame, length, spacing, target) {
	this.text = text;
	this.href = href;
	this.frame = frame;
	this.length = length;
	this.spacing = spacing;
	this.target = target;
	// Reference to the object's style properties (set later).
	this.ref = null;
}