function showpage(pagename) {
	var divs = document.getElementsByTagName("div");
	for (var i=0; i<divs.length; i++ ) {
		if (divs[i].className == "machin") {
			 if (divs[i].getAttribute("id") != pagename) {
				divs[i].style.display = "none";
			} else {
				divs[i].style.display = "block";
			}
		}
	}
}