title: How to keep changed form content when leaving and going back to HTTPS page? (works with HTTP)
body: <ol>
  <li>Enter/change something in a textarea</li>
  <li>Before submitting the form, leave the page (e.g. by clicking browser's back button)</li>
  <li>Go back to the edit page (e.g. by clicking the forward button)</li>
  </ol>
  
  <p>Expected result: the content entered in the textarea should still be there</p>
  
  <p>Actual result: </p>
  
  <ul>
  <li>with <strong>HTTPS</strong>: all changes are gone <em>(bad!)</em></li>
  <li>with <strong>HTTP</strong>: the changes are still there <em>(good!)</em></li>
  </ul>
  
  <p>Why is this happening when using HTTPS? How can I prevent this? Is the browser or the website responsible?</p>