When editing a post, the post text should be preserved when moving away from the form

[FransBouma]

If for instance, the user accidentally opens a new page in the current tab where they were editing a post, and click the Back button, due to https' nature, the form is cleared. This is frustrating. The autocomplete feature could help here, as it's a single form with 1 textfield. See: https://stackoverflow.com/a/14421723/44991