Q:

RFC: Better chat @mentions – A prototype

Status: 75% - We have a prototype to play with the UI
Previous RFC: RFC: Better chat @mentions
Problem Statement & Background
Please see the previous RFC.
Proposed solution
The feedback to the solution I proposed in the original RFC was overwhelmingly positive. We now have a prototype of the chat input box's behavior under the new regime. It incorporates some of the suggestions made in response to the original post.
This is just that: a prototype. I'm not looking for bug reports on every minor issue; rather, I'd like to know whether it feels comfortable and non-awkward for you to compose chat messages in this way, and if it in any way breaks your flow and muscle memory when chatting.
For now this is intended to work in desktop Chrome and Firefox, it may or may not work completely in other browsers. Again, finding cross-browser bugs is not the purpose of this RFC. Of course the final version is supposed to work in all our supported browsers, including mobile ones.
Link to the prototype: http://chat.meta.stackexchange.com/prototypes/mention
Known issues

Undo/redo is spotty at best. Not that it's great in the current chat input box, but I'd like it to be better before release.
The way that @mentions are displayed seems to suggest that you can interact with them (e.g. click on them to display the well-known user info popup), but that's not currently the case. See the next section for more.

Open questions

Can you work with this? Does it break the way that you're used to chatting? If so, how so?
If you use assistive technology (e.g. screen readers), does it work for you? I know our chat is anything but the archetype of an accessible web application, but I certainly don't want to make matters worse.
What should happen when you click a mention? Would you rather see the current behavior, which is closer to what you would expect from a normal text input box, or would you rather see the user info popup (or something else entirely)?
Relatedly: At the moment, the underlying @[123] is exposed when you move the text cursor onto a mention. On the one hand, this keeps the behavior closest to that of a "real" text box (in particular, Ctrl-A Ctrl-C Ctrl-V works in obvious way). On the other hand, this may be too much of a power user-only thing to expose (I am not suggesting to break copy&paste in either case). What are your thoughts on this?
Anything else?

If possible, when describing any behavior that felt irritating, also describe what you would've expected to happen instead.

A:

Treat the element as a single unit when deleting and copying it.
If you type @Mar and then press tab to auto complete then immediately press the delete button (or backspace on windows) it should delete the entire UI element and not just the ] at the end of the text version.  The same should go for copying; when it's highlighted I don't really want to see the text version either.

A:

Can you work with this? Does it break the way that you're used to chatting? If so, how so?

Oh, yes. It works very nicely. I don't like it flashing all text the entire time if you click anywhere near a user name, but I can live with that for now.

What should happen when you click a mention?

I would like to see single elements you can delete at once. Also, if possible, keep it the same size as the actual user name. That will prevent the flashing text.

would you rather see the user info popup (or something else entirely)?

That is a nice-to-have, but actually I seldom use it. Users I want to address are somewhere close in the chat log; I can always see their profile there.
Breaking copy/pasting is a bad idea, but the current repetitive clicks on backspace are just as annoying.

A minor bug now: when selecting all text, you can't unfocus it with your mouse. After a few clicks it works.

A:

Something small but cool, aka nice to have, would be a tooltip suggesting a closest match when trying to ping a non-existent user, e.g.:

Doesn't have to be complicated algorithm, just a simple characters match. I'm used to Chrome auto correct suggestions when typing (hey, got one even now, typed "existant" by mistake) and having such suggestion(s) would be awesome.

