function vorschau(url)
	{
        var fenster = document.all['if'+url.id];
        if(url.innerText == '[Vorschau Seite]')
        {
        if(fenster)
              {
               fenster.style.height = 400;
               fenster.style.visibility = 'visible';
               fenster.src = url.href;
               }
         else url.insertAdjacentHTML('AfterEnd', '<IFRAME id=if'+url.id+' width=100% height='+400+' SRC="'+url.href+'" ></IFRAME>');
         url.innerText = '[Vorschau schliessen]';
         }
         else
        {
         if(fenster)
              {
              fenster.style.visibility = 'hidden';
              fenster.style.height = 0;
              url.innerText = '[Vorschau Seite]';
              fenster.src = 'about:blank'; }
              }
         }