Songs Adjust Volume for all speakers

The Sonos iOS app allows you to easily adjust the volume of the current group of Sonos speakers.

I am looking to do something similar in Indigo.

Is it possible to control the volume for:

a) the Sonos speakers currently playing (with one button)?
b) a preconfigured group of Sonos speakers (with one button)?
c) can this be a slider control?

a) I think you need at least two buttons (volume up, volume down).
b) I added group volume actions a couple of releases ago, so using this action with the group coordinator should work.
c) There is not native slider that can be placed on a control page, but I've read that some others have created something close through a series of graphics.

The Sonos iOS app allows you to easily adjust the volume of the current group of Sonos speakers.

I am looking to do something similar in Indigo.

Is it possible to control the volume for:

a) the Sonos speakers currently playing (with one button)?
b) a preconfigured group of Sonos speakers (with one button)?
c) can this be a slider control?