title: Validate input type=file with onBlur
body: <p>I'm able to use onBlur to validate type=text or textarea inputs, however I haven't been able to get the same to work for type=file.  </p>
  
  <p>This works:</p>
  
  <pre><code>&lt;input type='text' name='sometextfield' size=30 class='input' onBlur="alert('Frell me dead, it works!');"
  </code></pre>
  
  <p>This does not (no error):</p>
  
  <pre><code>  &lt;input type='file' name='file_upload' size=30 class='input' onBlur="alert('Frell me dead, it works!');"&gt; 
  </code></pre>
  
  <p>What is the trick to validating type=file input boxes, on the fly?  I'd like to do this in vanilla Javascript.  I'm testing with Chrome 17.0.963.56 and Firefox 10.0.2 under Ubuntu.</p>
  
  <p>Thanks for tips/pointers.</p>