//Browser detection
var AgntUsr=navigator.userAgent.toLowerCase();
//alert(AgntUsr);
var DomYes=(document.getElementById)?1:0; 												// DOM
var NavYes=(AgntUsr.indexOf('mozilla')!=-1&&AgntUsr.indexOf('compatible')==-1)?1:0; 	// Netscape
var ExpYes=(AgntUsr.indexOf('msie')!=-1)?1:0; 											// IExplorer
var Opr=(AgntUsr.indexOf('opera')!=-1||AgntUsr.indexOf('opera')!=-1)?1:0; 				// Opera
var Opr5=(AgntUsr.indexOf('opera 5')!=-1||AgntUsr.indexOf('opera/5')!=-1)?1:0; 			// Opera 5
var Opr6=(AgntUsr.indexOf('opera 6')!=-1||AgntUsr.indexOf('opera/6')!=-1)?1:0; 			// Opera 6
var Opr7=(AgntUsr.indexOf('opera 7')!=-1||AgntUsr.indexOf('opera/7')!=-1)?1:0; 			// Opera 7
var DomNav=(DomYes&&NavYes)?1:0; 														// Netscape 6 up
var Exp5=(AgntUsr.indexOf('msie 5')!=-1)&&(AgntUsr.indexOf('gecko') == -1)?1:0;			// IE 5
var Exp55=(AgntUsr.indexOf('msie 5.5')!=-1)&&(AgntUsr.indexOf('gecko') == -1)?1:0;			// IE 5
var Exp6=(AgntUsr.indexOf('msie 6')!=-1)&&(AgntUsr.indexOf('gecko') == -1)?1:0;			// IE 5
var DomExp=(DomYes&&ExpYes)?1:0; 														// IExplorer 5 up
var Nav4=(NavYes&&!DomYes&&document.layers)?1:0; 										// Netscape 4
var Exp4=(ExpYes&&!DomYes&&document.all)?1:0; 											// IExplorer 4
var PosStrt=((NavYes||ExpYes)&&!Opr5)?1:0; 												// Can start
var OS="";	
var detect = navigator.userAgent.toLowerCase();
function checkIt(string) {
	place = detect.indexOf(string) + 1;
	thestring = string;
	return place;
}
//OS detection
if (checkIt('linux')) OS = "Windows";
else if (checkIt('x11')) OS = "Windows";
else if (checkIt('mac')) OS = "Mac";
else if (checkIt('win')) OS = "Windows";
else OS = "an unknown operating system";

//Dynamic content
function returnWinHeight() {
	var winHeight = 0;
	if (ExpYes && OS != "Mac") {
		if (document.compatMode && document.compatMode != "BackCompat")
			winHeight = document.documentElement.clientHeight;
		else
			winHeight = document.body.clientHeight;
	} else if (OS == "Mac" && Safari) {
		winHeight = window.innerHeight;
	} else {
		if (ExpYes) {
			if (document.compatMode && document.compatMode != "BackCompat")
				if(document.documentElement.clientHeight > 0)
					winHeight = document.documentElement.clientHeight;
				else
					winHeight = document.body.clientHeight;
			else
				winHeight = document.body.clientHeight;
		} else {			
			winHeight = window.innerHeight;
		}
	}
	return winHeight;
}

function changeDiv() {
	space = 30;
	if (document.getElementById("center").offsetHeight < returnWinHeight()) {	
		if (OS == "Mac" & ExpYes)
			document.getElementById("center").height = returnWinHeight() - space + "px";
		if (ExpYes) {
			if (document.getElementById("center"))
				document.getElementById("center").style.height = returnWinHeight() - space + "px";
		} else {
			if (document.getElementById("center"))
				document.getElementById("center").style.height = returnWinHeight() - space + "px";
		}
	}
}

//Error handling
function validateString(what) {
	if (what == "")
	return false;
	else
	return true;
}
function validateEmail(what) {
	var filter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
	if (filter.test(what)) 
		return true;
	else 
		return false;
}