I'm going to add this to the wish list, but thought I'd put it here for comment.
I think it would be very handy to have the same group level selection capability in the mute list as exists in the "File,Page Setup" dialog for hiding staves.
In other words, in vocal scores I often label the various staves as "Vocal", "Accomp", "Brass", "Winds", etc. In Page Setup, it is then very easy to hide an entire group of related staves.
Having a similar ability to quickly mute an entire group would be terrific.
Just last night I was wishing for exactly that, I would add my vote for such a facility.
Roelie