function swapTopNav(linkID,className) {
	document.getElementById(linkID).className = className;
}

//browser detection
var detect = navigator.userAgent.toLowerCase();
var OS,browser,total,thestring;
var version = 0;

if (checkIt('safari')) browser = "safari"
else if (checkIt('firefox')) browser = "firefox"
else if (checkIt('msie')) browser = "Internet Explorer"
else if (!checkIt('compatible'))
{
	browser = "Netscape Navigator"
	version = detect.charAt(8);
}
else browser = "An unknown browser";

if (!version) version = detect.charAt(place + thestring.length);

if (!OS) {
	if (checkIt('linux')) OS = "Linux";
	else if (checkIt('x11')) OS = "Unix";
	else if (checkIt('mac')) OS = "Mac";
	else if (checkIt('win')) OS = "Windows";
	else OS = "an unknown operating system";
}

function checkIt(string) {
	place = detect.indexOf(string) + 1;
	thestring = string;
	return place;
}

//writes stylesheet name, depending on browser
function getStylesheet() {
	document.write('<link rel="stylesheet" type="text/css" href="css/general.css" />');
	if (OS == 'Mac') {
		document.write('<link rel="stylesheet" type="text/css" href="css/firefox.css" />');
	}
	else {
		if (browser == 'Netscape Navigator') {
			document.write('<link rel="stylesheet" type="text/css" href="css/firefox.css" />');
		}
		else if (browser == 'firefox') {
			document.write('<link rel="stylesheet" type="text/css" href="css/firefox.css" />');
		}
	}
}

//preloads images
function preloadImages(){
	var siteImages=new Array()
	for (i=0;i<preloadImages.arguments.length;i++) {
		siteImages[i]=new Image();
		siteImages[i].src=preloadImages.arguments[i];
	}
}

//opens new window
function openWin(url,windowname) {
	newWin = window.open(url,windowname,'width=750,height=500,innerWidth=750,innerHeight=500,top=0,left=0,screenX=0,screenY=0,scrollbars=yes,resizable=yes,status=yes,toolbar=yes,location=yes,addressbar=yes');
	newWin.focus();
}

//opens new window
function openRefWin(url) {
	refWin = window.open(url,'reference','width=639,height=440,innerWidth=639,innerHeight=440,top=0,left=0,screenX=0,screenY=0,scrollbars=yes,resizable=yes,status=yes,toolbar=yes,location=yes,addressbar=yes');
	refWin.focus();
}

//opens new window
function openImageWin(url) {
	imgWin = window.open(url,'image','width=639,height=479,innerWidth=639,innerHeight=479,top=0,left=0,screenX=0,screenY=0,scrollbars=yes,resizable=yes,status=yes,toolbar=yes,location=yes,addressbar=yes');
	imgWin.focus();
}

//rollover function
function swap(iname,swapGfc) {
	document.images[iname].src = swapGfc;
}