title: Cancel Backspace back in all dynamic iframe pages recursively
body: <p>My asp.net application contains iframe element named "bodyFrm".
  bodyFrm content changes dynamically, the content pages contains iframe and more html elements.
  sometime the child page contains iframe with more child page.
  I want to cancel the action go to previous page when user pressed the backspace.
  I try to call CancelBackspace functoin in window.onkeydown event of main page,
  but it's called sometimes,not for every key press,
  how can I call the function for every key press in application ?
  I can't use jquery.</p>
  
  <p>in main page, works part time:</p>
  
  <pre><code>&lt;script type="text/javascript"&gt;
  document.onkeydown = CancelBackspace();
  function CancelBackspace(e){
    if(!e)
       e = event;
    if(e.keyCode == 8)
       return false;
  } 
  &lt;/script&gt;
  </code></pre>