function launch()
{
	window.open("practice1.html","mywindow","top=0,left=0,toolbar=no,status=no,location=no,menubar=no,resizable=1,width=655,height=605");
}
sfHover = function() 
{
	var sfEls = document.getElementById("nav").getElementsByTagName("LI");
	for (var i=0; i<sfEls.length; i++) 
	{
	sfEls[i].onmouseover=function() {
	this.className+=" sfhover";
	}
	sfEls[i].onmouseout=function() {
	this.className=this.className.replace(new RegExp(" sfhover\\b"), "");
	}
}
}
if (window.attachEvent) window.attachEvent("onload", sfHover);




function showlayer(layer){
var myLayer = document.getElementById(layer).style.display;
if(myLayer=="none"){
document.getElementById(layer).style.display="block";
} else { 
document.getElementById(layer).style.display="none";
}
}


function hide(layerName) { 
document.getElementById(layerName).style.display = 'none';
}

function show(layerName) { 
document.getElementById(layerName).style.display = 'block';
}