function check_login() {
	if (document.user_inf.login.value=="") {
		alert("The field Login is empty!");
		document.user_inf.login.focus();
		return false;
	}
	window.open("chkuser.php?login="+document.user_inf.login.value, "check", "height=100,width=300,scrollbars=no,resizable=no,toolbar=no");
	return false;
}
function check_email() {
	if (document.user_inf.email.value=="") {
		alert("The field Email is empty");
		document.user_inf.email.focus();
		return false;
	}
	window.open("chkuser.php?email="+document.user_inf.email.value, "check", "height=100,width=300,scrollbars=no,resizable=no,toolbar=no");
	return false;
}