showname="layer1"
function showPage(layername)
{

	if(document.all)
	{

			document.all[layername].style.visibility='visible'
			document.all[showname].style.visibility='hidden'
			showname=layername	

	}
	else if(document.layers)
	{

			document.layers[layername].visibility = "show"
			document.layers[showname].visibility = "hide"
			showname=layername

	}
	else{
		alert("No support of layer");
	    }
}