title: plupload - upload button works only if click is triggered programatically
body: <p>I am using plupload 1.5.7. I have two buttons on page:</p>
  
  <p><img src="https://i.stack.imgur.com/YmUth.png" alt="buttons"></p>
  
  <p>First one (Add new attachment) was used as browse_button in plupload configuration. When I click it, it doesn't work. Click event is executed, but file browser is not opened. But there is second button (Trigger add new attachment click), which only does this:</p>
  
  <pre><code>$('#TriggerAddNewAttachmentClickButton').click(function() {
      $("#AddNewAttachmentButton").click();
  })
  </code></pre>
  
  <p>So it only triggers click of the first button. It works fine. Clicking it opens file browser.</p>
  
  <p>How is this possible? This behavior is consistent between Firefox, Chrome and Internet Explorer.</p>
  
  <p>Obviously this is security related, because plupload uses tricks to hide input, but second method is not safer. I can't reproduce this issue in jsfiddle, it exists only in specific context, but maybe there is someone, who ecountered similar behaviour.</p>