var opera = (navigator.userAgent.indexOf('Opera') >= 0) ? true : false;
var dom = (document.getElementById) ? true : false;
var ie4 = (document.all && !dom) ? true : false;
var nn4 = (navigator.appName == "Netscape" || !dom) ? true : false;
var obj = (nn4) ? window:document;
var prevMenus = {};

function menuFlip(img, mode) {
	var menuId = null;
	var prevMenu = null;
	if (img) {
		var p = img.id.match(/^(\D*)/);
		menuId = p[1];
	}
	if (prevMenus[menuId] && prevMenus[menuId] != img) menuFlip(prevMenus[menuId], 'hide');
	if (img == null) return;
	var suf = "";
	var id = img.id+"s";
	if (mode == 'on') {
		suf = "a";
		showLayer(id);
		prevMenus[menuId] = img;
	} else {
		suf = "";
		hideLayer(id);
		prevMenus[menuId] = null;
	}
	img.src = img.src.replace(/[ac]?(\.[^.]+)$/, suf+"$1");
}

function showHideLayer(id, bShow) {
	var obj;
	var cmd = bShow? "visible" : "hidden";
	if (dom && !opera)
		obj = document.getElementById(id) && document.getElementById(id).style;
	else
		if (ie4 && !opera)
			obj = document.all[id] && document.all[id].style;
		else
			if (nn4) {
				obj = document.layers[id];
				cmd = bShow? "show" : "hide";
			}
	if (!obj) return;
	obj.visibility = cmd;
}

function showLayer(id) { showHideLayer(id, 1); }
function hideLayer(id) { showHideLayer(id, 0); }

function is_valid_email(email) {
	email = email.replace(new RegExp('/\(.*?\)/'), '');
	// var oRegExp = /^[A-Za-z0-9][-\w]*(\.[A-Za-z0-9][-\w]*)*@[A-Za-z0-9][-\w]*(\.[A-Za-z0-9][-\w]*)*\.[a-zA-Z]{2,4}$/;
	var oRegExp = /^[0-9a-zA-Z_][0-9a-zA-Z_.-]*[0-9a-zA-Z_-]@([0-9a-zA-Z][0-9a-zA-Z-]*\.)+[a-zA-Z]{2,4}$/;
	return oRegExp.test(email);
}