Stay on the page after clicking "Done" in the Notifications bar #2952

After opening a notification, I get to the page that triggered it (e.g. a PR or issue I subscribed to). At the top of the page, there is a light blue bar with buttons that act on the notification:

I'd like to have a quick way of marking the notification as "Done" (and maybe also the other actions) on that page without being redirected back to the Notifications page.

Two possible solutions I can imagine:

1. When clicking on the buttons while pressing the "Alt" keyboard button, the button action is executed, the notification bar disappears, but I stay on the page. When "Alt" is not pressed, the behavior doesn't change.
2. When clicking on the buttons, the button action is executed, the notification buttons change (e.g. after clicking "Done", the only valid action is now "Move to inbox"), but I stay on the page. To go back to notifications or close the notification bar, I have to click the respective button.

Similar to #2546.