Add ability to have volume control in default view

[Raketemensch]

It would be great to have the volume slider available in the top-level view instead of having to drill down into audio settings.

As someone who works while listening to classical music, which is full of dynamics, I have to change volume fairly often, and am trying to find a solution to handle it quickly.

This situation would be ideal -- just to be able to add the volume control to a custom layout.