How to view merge review comments and file changes in GitLab?

I'm performing a merge review (code review) in GitLab. I entered some file comments then the author responded to the comments and made some changes to the files. I can view the comment thread, and the relevant portion of the original file on the merge request Overview page. And a link there will take me to a diff between the original and changed files.

But how can I see the comment, response and file diff at the same time? Open the diff link in a new window?

GitLab version = Enterprise Edition 12.10.1-ee

(Newbie stackexchange user - Apologies for any breaches of etiquette.)

Check if GitLab 14.6 (December 2021) improves your use case:

View inline the change that outdated a merge request thread

When addressing review feedback in merge requests, you often change lines your reviewers have commented on.
In those comment threads, GitLab indicates that new changes were made.

However, to understand if those new changes address the feedback, reviewers would have to navigate away from the context of the discussion.

Now, when viewing threads related to old changes, you can view the new changes directly in the thread.
This improved context helps you review faster and more accurately.

See Documentation and Issue.

GitLab 16.2 (July 2023) adds:

Interactive diff suggestions in merge requests

When you suggest changes in a merge request, you can now edit your suggestions more quickly. In a comment, switch to the rich text editor and use the UI to move up and down the lines of text. With this change, you can view your suggestions exactly as they will appear when the comment is posted.

The rich text editor is a new way of editing in GitLab. It’s available in merge requests, but also available alongside the plain text editor in issues and epics.

We plan to have the rich text editor available in more areas of GitLab soon and we are actively working on that. You can follow our progress here.

See Documentation and Issue.