function change_tab(newtab){
	var divs = document.getElementsByTagName("div");
	for (var i=0; i<divs.length; i++){
		var divid = divs[i].id;
		if (divid.length > 0 && divid.substring(0, 4) == "tab_"){
			if (divid == newtab){
				divs[i].className = "tabbox selected";
				document.getElementById('link' + divid).className = "tab activeTab";
			} else {
				divs[i].className = "tabbox hidden";
				document.getElementById('link' + divid).className = "tab";
			}
		}
	}
}