New comment highlight after following a notification persists in an unexpected way.

Note: This ticket is a response to the behavior that was implemented in T281471.

User story

As someone who clicked a notification, from within Echo, about a new comment posted in a topic I am subscribed to, I want to be able to easily and quickly locate that comment on the talk page to which it is posted, so that I can understand the context in which the comment exists.

Revised behavior

Messages should disappear when a contributor clicks anywhere else on the page

Context

Comments about this were made by @Tacsipacsi after trying out an early demo, and by @Ryasmeen during pre-deployment QA:

In T281471#7117992, @Tacsipacsi wrote:

Expected
[…]
The highlight […] never fades.

I don’t like when such highlights are “stuck” on the page until I navigate away; maybe I already do something entirely different. I like GitHub’s approach: when I open an anchor link (e.g. https://github.com/wikimedia/parsoid/pull/5#issuecomment-371981298), it highlights the comment, this highlight doesn’t fade out automatically, but it disappears immediately when I click anywhere on the page outside of that comment.

In T274279#7156654, @Ryasmeen wrote:

2. When you click on a notification item, it takes you to the correct position on the talk page and highlights the comment. However, the highlight remains despite moving focus to elsewhere on the page. That means, even when you click on a Reply link for another comment on that talk page, the highlight stays for the notified comment, thus making it look confusing. It only goes away when a new comment gets highlighted after posting or after refreshing the page. cc: @iamjessklein

Done

• Revised behavior is specified
• Revised behavior is implemented