In the past there was an issue (reported here) where pressing the
Enter key to select an IME suggestion would also submit the comment.
The good news is that we believe to have found the proper way to handle this, allowing you to use the
Enter key to select your IME suggestion, while also still being able to use
Enter to submit the comment if you're not in the middle of composing a word.
As such, we've enabled the new IME behavior network-wide.
I've written a blog post with the technical details of this change.