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

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));
}