[Aetae]

Пояснение к тому что я имел ввиду изначально:

<script>
  var elem = window;
  alert([ ' Normal window:',
    'elem.setInterval:\t\t' + !!elem.setInterval,
    'elem != window:\t\t' + (elem != window),
    '!elem.frameElement:\t' + !elem.frameElement,
    (elem.setInterval && ( elem != window && !elem.frameElement ) ) 
  ].join('\n'))
</script>
<input type="button" onclick="
  var elem = window.open('about:blank');
  alert([ ' New window:',
    'elem.setInterval:\t\t' + !!elem.setInterval,
    'elem != window:\t\t' + (elem != window),
    '!elem.frameElement:\t' + !elem.frameElement,
    (elem.setInterval && ( elem != window && !elem.frameElement ) ) 
  ].join('\n'))
" value="click me">
<iframe src="about:blank" onload="
  var elem = this.contentWindow;
  alert([ ' Frame window:',
    'elem.setInterval:\t\t' + !!elem.setInterval,
    'elem != window:\t\t' + (elem != window),
    '!elem.frameElement:\t' + !elem.frameElement,
    (elem.setInterval && ( elem != window && !elem.frameElement ) ) 
  ].join('\n'))
" style="position:absolute;top:-800px;">