function openPopup(window_width,window_height) {
	var h,w
	h = screen.height //height of screen, not just the parent window
	w = screen.width //width of the screen, not just the parent window
	var l,t
	l = parseInt((w-window_width)/2)
	t = parseInt((h-window_height)/2)
	popupWin = window.open('calendar.html','open_window','status,dependent,width='+window_width+',height='+window_height+',left='+l+',top='+t)
	}
	
	 browserName = navigator.appName;          
			   browserVer = parseInt(navigator.appVersion);
				   if ((browserName == "Netscape" && browserVer >= 3)
					  || (browserName == "Microsoft Internet Explorer" && browserVer >= 4) ) 
				   version = "n3";
				   else version = "n2";
				   
				   if (version == "n3") {                
				   arrow_nav1on = new Image(37, 149);          
				   arrow_nav1on.src = "./slideshow/images/tour/arrow_lt_on.gif";
				   arrow_nav2on = new Image(37, 149);
				   arrow_nav2on.src = "./slideshow/images/tour/arrow_rt_on.gif";
				   
				   arrow_nav1off = new Image(37, 149);       
				   arrow_nav1off.src = "./slideshow/images/tour/arrow_lt.gif";
				   arrow_nav2off = new Image(37, 149);
				   arrow_nav2off.src = "./slideshow/images/tour/arrow_rt.gif";
			}
	
	function img_act(imgName) {
			if (version == "n3") {
			imgOn = eval(imgName + "on.src");
			document [imgName].src = imgOn;
			}
	}
	
	function img_inact(imgName) {
			if (version == "n3") {
			imgOff = eval(imgName + "off.src");
			document [imgName].src = imgOff;
			}
	}