title: Dropzone class .dz-started & click problems when "previewsContainer" option has been set
body: <p>I use the JavaScript Dropzone.js on my Web page with following code:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>Dropzone.options.myDropzone = { 
    previewsContainer: ".dropzone-previews", // ?dz-started
  };</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;form action="assets/plugins/dropzone/upload.php" class="dropzone" id="my-dropzone"&gt;
    &lt;button type="submit" class="btn btn-lg btn-success"&gt;ارسال فایل&lt;/button&gt;
    &lt;div class="dropzone-previews"&gt;&lt;/div&gt;               
  &lt;/form&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>I need to do this configuration because the page which I am try to install Dropzone on it,is a working page which I want to maintain previous codes as much as possible.
  but with this configuration 2 problems arises:<br/>
  1- When I add a file to Dropzone, the "dz-started" css class, would not add to html dropzone element and in consequence the message "drop file here. . . " don`t disapear.<br/>
  2- When I add multiple files to Dropzone, from that moment some of my clicks around file thumbnails, do not opens the file dialogue.
  <br/>
  please help me, thank you.</p>