function fenster(datei,x,y) 
 {
 var hori = screen.availWidth;
 var verti = screen.availHeight;
 F1 = open("popup.php","Anzeige","width="+x+",height="+y+",left="+((hori - x- 10)* .5)+",top="+((verti - y- 30)* .5)+",dependent=yes,toolbar=no,location=no,directories=no,status=no,menubar=no ");
 F1.focus(); 
 }