function go()
{
  if (document.min_form.sn.value.length<1) {
    alert("Du skal huske at indtaste dit serie nummer");
    return false;
  } ;
}

newwin = null;
function doPopup(f) {
  newwin = window.open('', 'Betaling','scrollbars,status,width=550,height=600');
  newwin.focus();
  if(!self.name) { self.name = 'shopwin'; }
  if (!newwin.opener) { newwin.opener = self; }
  f.opener.value = self.name;
  return true;
} 

function doButtons(picimage) {
document['picture'].src=picimage;
}

function PopWin(url,h,w) { var ww = 480, wh = 340, leftPos = null, topPos = null; 

IE=(document.all)?true:false; 
var wh = (IE)?document.body.clientHeight : window.innerHeight; 
var ww = (IE)?document.body.clientWidth : window.innerWidth; 

if (top.screen){ 
  if (screen.width){ 
    leftPos = Math.round((ww-w-10)/2); 
    topPos = Math.round((wh-h-29)/2); 
  } else { 
    leftPos = 50 
    topPos = 50 
  } 
} 

 popupWin = window.open(url, 'popup', 'height=' + h + ',width=' + w + ',top=' + topPos + ',left=' + leftPos + '') 
}