function openWindow(url,  w, h) {
var winbreite = (screen.width - w) / 2;
var winhoehe = (screen.height - h) / 2;
winprops = 'height='+h+',width='+w+',top='+winhoehe+',left='+winbreite+',scrollbars='+scroll+',resizable';
win = window.open(url, "fenster", winprops);
win.window.focus();
}