function expand_menu(id) {
	i = 0;
	while (true) {
		i++;
		eval("if (typeof(pr_"+id+"_"+i+") == 'undefined') i=1000;");
		if (i==1000) break;
		eval("if(pr_"+id+"_"+i+".style.display == 'none') {pr_"+id+"_"+i+".style.display = 'block'} else {pr_"+id+"_"+i+".style.display = 'none'}");
	}
}