function showlayer(layer,hideLayer,hideLayer2){
        var myLayer = document.getElementById(layer).style.visibility;

        document.getElementById(hideLayer).style.visibility="hidden";
	document.getElementById(hideLayer2).style.visibility="hidden";

        if(myLayer=="hidden"){
                document.getElementById(layer).style.visibility="visible";
        } else {
                document.getElementById(layer).style.visibility="hidden";
        }
}