function Venster(URL) {
venster = window.open(URL, 'popupvenster', 'width=690, height=680, left=80, top=80, resizable=yes, menubar=yes, scrollbars=yes, status=no, toolbar=no');
}

function roll(img_name, img_src)
   {
   document[img_name].src = img_src;
   }