Spun out of T217296:
When visiting Special:Notifications and clicking the filter icon a NotificationsFilterOverlay is displayed.
Despite being an incredibly simple component, NotificationsFilterOverlay extends Overlay
- Use Overlay.make to make the filters overlay
- Visit https://en.m.wikipedia.org/wiki/Special:Notifications
- Click the filter icon
- Confirm the filter overlay displays and can be closed via close icon or back button