DOM = (document.getElementById) ? true : false;
NS4 = (document.layers) ? true : false;
IE = (document.all) ? true : false;
IE4 = IE && !DOM;
NS = (navigator.appName=="Netscape") ? true : false;
NS6 = NS && DOM;
MAC = (navigator.appVersion.indexOf("Mac") != -1);
 
function preload(imgObj,imgSrc) {
	if (document.images) {
		eval(imgObj + 'On = new Image()')
		eval(imgObj + 'On.src = imgSrc + "roll.gif"')
		eval(imgObj + 'Off = new Image()')
		eval(imgObj + 'Off.src = imgSrc + ".gif"')
	}
}

function img_act(imgName) {
	if (document.images) {
		document[imgName].src = eval(imgName + "On.src");
	}
}

function img_inact(imgName) {
	if (document.images) {
		document[imgName].src = eval(imgName + "Off.src");
	}
}

function changeImages() {
	if (document.images) {
    	for (var i=0; i<changeImages.arguments.length; i+=2) {
      		document[changeImages.arguments[i]].src = eval(changeImages.arguments[i+1] + ".src");
    		}
		}
}

function openWindow(windowURL,windowName,windowWidth,windowHeight) {
	newWindow = window.open(windowURL,windowName,'width='+windowWidth+',height='+windowHeight+',toolbar=0,location=0,directories=0,status=0,menuBar=0,scrollbars=1,resizable=0');
	newWindow.focus(); 
}