function centerPopup(popup_name,popup_url,popup_width,popup_height,scrolls, menubars, myWidth, myHeight,reqURL)
{
 if(!myWidth) {myWidth = 10;}
 if(!myHeight){myHeight = 50;}
 if(!scrolls){scrolls = 'no';}
 if(!menubars){menubars = 'no';}
 var popup_left = (window.screen.width/2) - (popup_width/2 + myWidth);
 var popup_top = (window.screen.height/2) - (popup_height/2 + myHeight);
 var fenster = window.open(popup_url ,popup_name,"toolbar=no,location=no,status=no,menubar=" + menubars + ",scrollbars=" + scrolls + ",resizable=no,width=" + popup_width + ",height=" + popup_height + ",left=" + popup_left + ",top=" + popup_top + ",screenX=" + popup_left + ",screenY=" + popup_top);
 fenster.focus();
}