Prompt before switching comments, leaving page, updating post whilst editing a comment in the edit post screen

[polevaultweb]

This was proposed here https://core.trac.wordpress.org/ticket/29457#comment:4 by @chriscct7.

1. Edit any post or page that has at least one comment in the post editor.
2. Make changes to the comment / add new comment
3. Attempt to leave the page in the browser, update the post, or click quick edit on another comment.
4. The changes are lost.

We need to prompt the user that their changes will be lost and handle the response.

Similar implementation that can possibly be leveraged - https://core.trac.wordpress.org/attachment/ticket/21845/21845.3.patch

Would need to build on the solution of https://core.trac.wordpress.org/ticket/29457#comment:4 when dealing with a user updating the post during a comment edit.

[rachelbaker]

Makes sense to me, moving to Future Release awaiting a patch.

[polevaultweb]

Patch refreshed

[polevaultweb]

@chriscct7 still applying cleanly - can we get into 4.6?

[rachelbaker]

Refresh with minor documentation and function name edits

[rachelbaker]

In 37303:

Comments: Keep comments safe in the Edit Post screen.

Warns users that have added a new Comment or began editing an existing without saving their changes, before they press the “update” button which would wipe out their comment changes.

Fixes #32818.

Props polevaultweb.