function popup(url){
var winl = (screen.width - 600) / 2;
var wint = (screen.height - 400) / 2;
winprops = 'height=400,width=600,top='+wint+',left='+winl+',scrollbars=yes,toolbar=yes,resizable';
win = window.open(url, 'printversie', winprops)
if (parseInt(navigator.appVersion) >= 4) { win.window.focus(); }
}