Messaging: unposted content alert

[fnisen]

We should notify the user when they're navigating away without posting content in the Dashboard or Discussions. This can happen in several cases:

1. Completed status update, but not posted
2. Composed message, but not posted
3. Composed reply to status update or message, but not posted

@vikasrohit can you apply the same approach you used for detecting when users have unsaved content in their Specifications?

[vikasrohit]

@fnisen How do we want to handle the case where user hasn't completed the post i.e. either title or content is not filled yet but one of them has some content. This means user has something unposted but the post is yet to be completed.

[fnisen]

@vikasrohit good question. Let's prompt them in that case to the return to the post. The action in either case would be to take them back to the post itself, not to actually post on their behalf.

[vikasrohit]

Okay. Just to be clear, we would show the alert even if the user has only typed one of title and content of the post.

[vikasrohit]

@fnisen
-- Implemented the required behaviour with Discussions page. Took liberty to implement the same behaviour when user has unposted content and tries to change the thread from the left panel of thread list or clicks on the + to create new thread.
-- Implemented the required behaviour with Dashboard page.

Please check the behaviour in dev and let me know if you find anything not working or not as expected. It took more than expected time because of possibility of different sequences of user actions with and without unposted contents.