function checkform(form) {
	if (checkfields(form, true))
		return true;
	alert("Mindestens ein wichtiges Formularfeld ist leer.");
	return false;
}

function checkall(form) {
	if (checkfields(form, false))
		return true;
	alert("Mindestens ein Formularfeld ist leer.");
	return false;
}

function checkfields(form, omitfiles) {
	for (var i = 0; i < form.elements.length; i++) {
		var elem = form.elements[i];
		if (elem.type == "file" && omitfiles)
			continue;

		var val;
		if (elem.type == "select-one") {
			var idx = elem.selectedIndex;
			val = elem.options[idx].value;
		} else {
			val = elem.value;
		}

		if (val == "" || val == " ")
			return false;
	}
	return true;
}