There is no username popup suggesting completion when typing an editor's user name prefix.

**Steps to reproduce:**

1. Find a post by AUser that was edited by UserB
1. Write a comment addressing `@UserB`

**Expected results:**

When having typed `@U`, the completion popup should suggest `@UserB`

**Actual results:**

No popup, as if there were no such user in the list of addressable users.

> ![enter image description here][1]

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[The Meta post on this feature states](http://meta.stackoverflow.com/questions/43019/how-do-comment-replies-work/43020#43020); while referencing [this answer](http://meta.stackoverflow.com/questions/36052/allow-post-editor-to-see-comments-directed-at-him/36055#36055):

> Notifications apply to the author, commenters, and editors of the question or answer that you are commenting on—users not in that list cannot be notified. You can also notify a ♦ moderator who closed the question. 

Since the popup can easily be seen as an indicator whether the user whose name I'm typing will receive my message, this behavior suggests that editors will not be notified, [while they actually are](http://superuser.com/questions/252673/asus-eee-win7-x86-service-pack-1-failure-code-80073701-unknown-error). This is why I classified this as a **bug**.


  [1]: https://i.sstatic.net/i0wt0.png