function switch_label(obj) {
	obj.className = 'focus';
	var name = obj.name;
	var val  = obj.value;
	label = 'label_' + name;
	startval = document.getElementById(label).innerHTML;
	document.getElementById(label).className='visible';
	if(val == startval) {
		obj.value = '';
	}
	return false;
}

function check_mailform(form) {
	if (!is_filled(form.name))             { alert('Bitte geben Sie Ihren Namen an'); form.name.focus(); return false; }
	if (!is_filled(form.email))            { alert('Bitte geben Sie Ihre E-Mail-Adresse an'); form.email.focus(); return false; }
	if (!is_valid_email(form.email.value)) { alert('Bitte geben Sie eine gueltige E-Mail-Adresse an'); form.email.select(); return false; }
	return true;
}

function is_filled(elm) {
	var label   = 'label_' + elm.name;
	var def_val = document.getElementById(label).innerHTML;
	if (elm.value == '' || elm.value == null || elm.value == def_val) {
		return false;	
	}
	return true;
}

function is_valid_email (emailStr) {
	var emailPat=/^(.+)@(.+)$/
	var specialChars="\\(\\)<>@,;:\\\\\\\"\\.\\[\\]"
	var validChars="\[^\\s" + specialChars + "\]"
	var quotedUser="(\"[^\"]*\")"
	var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/
	var atom=validChars + '+'
	var word="(" + atom + "|" + quotedUser + ")"
	var userPat=new RegExp("^" + word + "(\\." + word + ")*$")
	var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$")
	
	var matchArray=emailStr.match(emailPat)
	if (matchArray==null) {
		return false
	}
	var user=matchArray[1]
	var domain=matchArray[2]
	
	if (user.match(userPat)==null) {
		return false
	}
	
	var IPArray=domain.match(ipDomainPat)
	if (IPArray!=null) {
		  for (var i=1;i<=4;i++) {
			if (IPArray[i]>255) {
			return false
			}
		}
		return true
	}
	
	var domainArray=domain.match(domainPat)
	if (domainArray==null) {
		return false
	}
	
	var atomPat=new RegExp(atom,"g")
	var domArr=domain.match(atomPat)
	var len=domArr.length
	if (domArr[domArr.length-1].length<2 || 
		domArr[domArr.length-1].length>3) {
	   return false
	}
	
	if (len<2) {
	   return false
	}
	return true;
}