var it_pref="it_";
var fr_pref="fr_";

function xlang()
{ var actual_url, ix, ixe, base_url, new_page;

  actual_url=window.location.href+"";
  ix=actual_url.lastIndexOf("/");
  if   ( ix>-1 && ix<actual_url.length) 
         ix++;
  else   ix=0;

  ixe=actual_url.lastIndexOf("#");
  if   ( ixe == -1 ) 
         ixe = actual_url.length-ix;
  else   ixe = ixe-ix;

  base_url=actual_url.substr(0,ix);
  new_page=actual_url.substr(ix, ixe);

       if   ( new_page.indexOf(it_pref) > -1 )
              new_page=new_page.replace(it_pref, fr_pref);
  else if   ( new_page.indexOf(fr_pref) > -1 )
              new_page=new_page.replace(fr_pref, it_pref);
//  alert("actual_url:"+actual_url+"\nnew_page:"+new_page);
  window.location.href=base_url+new_page;
  return true;
}