function isEmailValid(szEmail) {
	var filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
	return filter.test(szEmail)
}

function checkVal(oField, szValue) {
	if (oField.value == szValue) {
		oField.value = ""
	}
	else if (oField.value == "") {
		oField.value = szValue
	}
}

function addLoadEvent(func) {
	var oldonload = window.onload;
	if (typeof window.onload != 'function') {
		window.onload = func;
	} else {
		window.onload = function() {
			if (oldonload) {
				oldonload();
			}
			func();
		}
	}
}