When e.g. connecting to a network with captive portal, it leaves you sitting there wondering what's going on. The notification won't time out until it becomes visible again but still there's been complaints that the notifications go missing.
This patch makes them move out of the way vertically. It is pretty crude but covers the majority ("System Tray covers notifications") case.

When there's many notifications, it can look a bit odd as they move down and then the lower part is hidden as notifications may only occupy 2/3 of vertical height even when shifted.
Didn't test what happens if you have a giant notification on a small screen, it will probably end up partially off screen
Could also be odd now if you open notification history, you'll see your notifications twice I guess