_iframeLog = {};
document.addEventListener('DOMNodeInserted'
  ,function(e) {
    var elem = e.target;
    if ((elem instanceof HTMLIFrameElement) && elem.id)
      _iframeLog[elem.id] = elem.src;
  }
  ,false
);
opera.addEventListener('BeforeEvent.load'
  ,function(e) {
    var target = e.event.target;
    if ((target instanceof HTMLIFrameElement) && target.id && (typeof _iframeLog[target.id] != 'undefined')) {
      if (_iframeLog[target.id] != target.src) {
        delete _iframeLog[target.id];
        e.preventDefault();
      }
    }
  }
  ,false
);