using Enter to select @username after using arrow keys causes message to send

[Brianna Rainey]

Typing @Jo and hitting Enter will fill in @Joanne for me. However if I want to mention @John, I have to type another character or use the mouse, because the arrow keys can select another result for @Jo but the Enter key functions as the "send message" key again once I use the arrows keys. This has caused me to send half-written usernames a few times.

I'm using Ubuntu 14.04 but this also happens on 16.04.