function historyBack() {
	if(document.referrer.indexOf('www.liquidmusik.net') != -1) {
		history.back();
	} else {
		window.location.href = "http://www.liquidmusik.net";
	}
}

function openCenteredWindow(url, width, height) {
    var left = parseInt((screen.availWidth/2) - (width/2));
    var top = parseInt((screen.availHeight/2) - (height/2));
    var windowFeatures = "width=" + width + ",height=" + height + ",status=0,resizable=0,menubar=0,left=" + left + ",top=" + top + "screenX=" + left + ",screenY=" + top;
    window.open(url, "_blank", windowFeatures);
}