function openCenteredPopup(url, name, breite, hoehe, extras) {
	if (extras != "")
		extras = "," + extras;
	var options = "width=" + breite + ",height=" + hoehe + ",left=" + getCenteredLeft(breite) + ",top=" + getCenteredTop(hoehe) + extras;
	window.open(url, name, options);
}

function openCenteredOffsetPopup(url, name, breite, hoehe, offsetX, offsetY, extras) {
	if (extras != "")
		extras = "," + extras;
	window.open(url, name, "width=" + breite + ",height=" + hoehe + ",left=" + (getCenteredLeft(breite) + offsetX) + ",top=" + (getCenteredTop(hoehe) + offsetY) + extras);
}

function getCenteredLeft(breite) {
	return ((screen.availWidth / 2) - (breite / 2));
}

function getCenteredTop(hoehe) {
	return ((screen.availHeight / 2) - (hoehe / 2));
}

function toggleDisplayById(id) {
	var element = document.getElementById(id);
	if (element.style.display == "none") {
		element.style.display = "";
	} else {
		element.style.display = "none";
	}
}

function displayById(id, displayValue) {
	var element = document.getElementById(id);
	 if (displayValue === undefined ) {
		 element.style.display = "";
	 } else {
		 element.style.display = displayValue;
	 }
}

function hideById(id) {
	var element = document.getElementById(id);
	element.style.display = "none";
}

function clearById(id) {
	var element = document.getElementById(id);
	element.value = "";
}

function clearCbById(id) {
	var element = document.getElementById(id);
	element.checked = false;
}

function toggleDisplayForArray(elements) {
	for (var i=0; i < elements.length; i++)
		toggleDisplayById(elements[i]);
}