function addLoadEvent(func) {
  if (typeof window.onload == 'function') {
    var oldFunc = window.onload;
    window.onload = function() {
      oldFunc();
      func();
    }
  } else {
    window.onload = func;
  }
}

function prepareTourPhotos() {
  var i, href, photo, photos;
  if (!(photos = document.getElementById('tour-photos'))) return;
  photos = photos.getElementsByTagName('a');

  for (i = 0; photo = photos[i]; i++) {
    photo.setAttribute('target', 'new');
    photo.onclick = function() {
      var title = this.getAttribute('title');
      var src = this.getAttribute('href');
      var photo = window.open('inc/frame.php?src='+src+'&title='+title, 'photo', 'height=375,width=500');
      return false;
    }
  }

}

addLoadEvent(prepareTourPhotos);