The Solus team says that the Solus is complete, I disagree. The notification center should have other functions such as video thumbnail and the possibility of answering messages and emails.
When you click the notification the application does not open

Err, I doubt they said it was complete. Otherwise, the project is done. It's a moving/chasing target.

It' s never been once claimed that Raven is feature complete, I have no idea where you got that from. There are significant improvements and changes I have planned for Raven for Budgie 11, however Budgie 10.5 is effectively feature frozen, which means no more features will be added to it, since every new feature or function that gets added is one more I have to strongly consider for porting over to Budgie 11.

    Building on that:

    The notification center should have other functions such as video thumbnail and the possibility of answering messages and emails.

    Messages and emails are still just notifications, in accordance with the Desktop Notifications Specification. I have not yet seen any specific support in the spec for the kinds of notifications you're thinking of (with the ability to reply). You're able to specify a limited set of actions, like clicking a "Reply" button which would open up the application to that view, but other than that it isn't supported in the spec.

    Video thumbnail is something I don't see any value-add in. You're not going to be watching a video in Raven. There are various Raven widgets which are planned such as Weather, Stocks, and RSS ("News"), but to do that there needs to be a Raven API, which is targeted for Budgie 11.

      JoshStrobl You're able to specify a limited set of actions, like clicking a "Reply" button which would open up the application to that view, but other than that it isn't supported in the spec.

      That's also the responsibility of the programs sending the notifications, right? Thus it isn't even Budgie's problem.

          EbonJaeger The responsibility on our part would only go so far as implementing that aspect of the spec if it even existed, but yea it'd mainly fall on applications to implement the support.

              JoshStrobl I read some articles regarding this and still well that is not the team's thinking, thanks for the patience and clarification

                JoshStrobl it's complicated. but is it possible within the limitations cited to give more functions to the notification center?