Add Notification type in-app popup

I'd also like the in-app notification to be more prominent — the user should have to explicitly dismiss it.

When "my" application goes offline for maintenance/an upgrade, I create a notification in IAM beforehand to alert all users. I use the in-app notification for this. The other two notification types (an email message, a message with a deep link) aren't suitable for my purpose.

However, the in-app notification falls short for this goal. The message only appears briefly on screen and then disappears automatically, similar to some error messages. But there are also notifications that stay on screen until the user closes them — such as the message shown when data can't be displayed on the open screen.

I'd like that same behavior (staying visible until dismissed) for the notification that the application is going offline. That would make it much clearer to users that they need to save their work.

A notification that disappears on its own risks being missed entirely if the user isn't looking at the screen at that exact moment, or is focused on something else. For a message this important — warning users before an outage — a persistent notification that requires explicit dismissal would greatly reduce the risk of users losing unsaved work.