Redesign for 3.10
The purpose for a facelift is to visually improve the presentation of the messages on the lock curtain and to allow to switch to the application providing the notification after authentication.
Notifications stack and push older notification as they arrive. Media controls always stay on top. No scrolling is to be used for notifications.
If the number of items is bigger than the available vertical space (which includes a height of approximately 2 bubbles for top and bottom padding) or the maximum cap of 6 items, the overflown bubbles group at the bottom. Urgent notifications are kept above taking precedence over recency.
To activate the app that provided the notification, double click the bubble. Upon the first click, the text label changes to "click to activate Chat". Unless another click happens, the label times out to change to the notification again (+-2s). Double tapping the overflow bubbles at the bottom will not activate a specific application, but open the message tray after a successful authentication.