Add ability to "drag in" the notification view like the notifications

[AlexGustafsson]

Just how the notifications are "dragged in" by using two fingers from the right side of the touchpad, the notification view could be dragged in from the left of the screen.

[AlexGustafsson]

This would solve the issue with the notification view being covered by macOS's notifications. It might however be a bit cumbersome as many applications use the left of the screen for navigation, meaning the notification view would get in the way of the user.