function block (nr) {
	if (document.layers) {
		var current = (document.layers[nr].display == 'none') ? 'block' : 'none';
		document.layers[nr].display = current;

	} else if (document.all) {
		var current = (document.all[nr].style.display == 'none') ? 'block' : 'none';
		document.all[nr].style.display = current;

	} else if (document.getElementById) {
		var current = (document.getElementById(nr).style.display == 'none') ? 'block' : 'none';
		document.getElementById(nr).style.display = current;
	}
	
	document.cookie = "" + nr + "=" + current;
}