title: Bringing back an "overridden" window method
body: <p>If I reset window.alert to be some other function, is there any way for me to restore it w/o first "saving" it? </p>
  
  <p>For example:</p>
  
  <pre><code>window.alert = function() { };
  </code></pre>
  
  <p>After doing that, is there a way of restoring window.alert() to what it used to be? (btw: asking this only for "predefined" DHTML objects - not for random js objects)</p>