Mention issues: PostMessage is only sent once. Keyboard doesn't work

[juliusknorr]

Describe the Bug

While working on emitting notifications for user mentions in the Nextcloud integration I noticed a couple of issues around mentions that are related to the Collabora side of the implementation.

It would be great to address those to make the mentions feature more flawless.

Steps to Reproduce

1. Use the Nextcloud integration with Collabora
2. Type @ to insert a mention
3. Start typing and search for a user

• Currently the search is only triggered once on the first character press @a. This is especially a problem for large instances with lots of users where the first result set would not contain all of the users. Instead there should be a debounced fetching of users while typing. You also see that only one postmessage is sent to Nextcloud.
• Clicking is required to insert a mention, having one match an pressing enter does not work

Additional Context

Latest master branch of online

[timur-g]

#7923 seems related where double @@mention may work.

[Rash419]

https://github.com/Rash419/online/commits/debounce-mention-user-query/ I will create a PR once #10145 is merged : )