function addPopupHandlers() {
  if (!document.getElementById('content')) {
    return;
  }

  var links = document.getElementById('content').getElementsByTagName('a');

  for (var i = 0, n = links.length; i < n; i++) {
    var rel = links[i].getAttribute('rel');

    if (rel == 'external') {
      links[i].onclick = function() {
        window.open(this.href, "Externe Seite").focus();
        return false;
      };
    }
    if (rel == 'popup') {
      links[i].onclick = function() {
        window.open(this.href, "Produktinformation", "width=600,height=600,scrollbars=yes,resizable=yes").focus();
        return false;
      };
    }
    if (rel == 'competition-popup') {
      links[i].onclick = function() {
        window.open(this.href, "Gewinnspiel", "width=600,height=700,scrollbars=yes,resizable=yes").focus();
        return false;
      };
    }
  }
}
addLoadEvent( addPopupHandlers );

function addLoadEvent(func)
{
  var oldonload = window.onload;

  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      oldonload();
      func();
    }
  }
}

function addUnloadEvent(func)
{
  var oldonunload = window.onunload;

  if (typeof window.onunload != 'function') {
    window.onunload = func;
  } else {
    window.onunload = function() {
      oldonunload();
      func();
    }
  }
}