function open_pic(bild){
var breite = screen.availWidth;
var hoehe = screen.availHeight;


pics = window.open("files/popup.php?bild="+bild,"pics","width=400, height=400, top="+(hoehe/2-200)+", left="+(breite/2-200)+", location=no, menubar=no, status=no, toolbar=no, resizable=yes, scrollbars=no")
}