title: How do I numerically rename files in Plupload before they're uploaded?
body: <p>I am using the Plupload jQuery UI widget as a basis for my uploader. The widget allows the user to drag reorder the added files.</p>
  
  <p>Upload is begun automatically upon the submission of a form, not manually by the user. During the upload, the UI is blocked so the user can't add anymore files.</p>
  
  <p>Before the upload begins, I need to rename all of the files to upload numerically so that the first file to be uploaded (the one at the top of the jQuery UI widget list) is '1', the second '2' and so on.</p>
  
  <p>For instance, given the following list:</p>
  
  <pre><code>bob.jpg
  ann.jpg
  doug.jpg
  chris.jpg
  </code></pre>
  
  <p>I want to have them renamed:</p>
  
  <pre><code>1.jpg
  2.jpg
  3.jpg
  4.jpg
  </code></pre>
  
  <p>This works when the user adds new files or removes existing files. What doesn't work is <strong>when the user drag reorders the files</strong>. Here is my instantiation code for the uploader:</p>
  
  <pre><code>$('#' + div_id).plupload({
    runtimes: 'html5, flash, silverlight',
    url: 'upload',
    unique_names: false,
    rename: true,
    sortable: true,
    buttons: { browse: true, start: false, stop: false },      
  
    // Flash settings
    flash_swf_url: 'js/plupload/plupload.flash.swf',
  
    // Silverlight settings
    silverlight_xap_url : 'js/plupload/plupload.silverlight.xap',
  
   init: {
     QueueChanged: function(up) {
       for (var i = 0; i &lt; up.files.length; i++) {
         up.files[i].name = (i+1);
       }
     }
   }
  });
  </code></pre>
  
  <p>I can't figure out how to detect when the user drag reorders. Failing that, I don't see an event that fires when the upload of the queue first begins.</p>