Master for submasters

I would like to see a new type of (master) fader added. A master for submasters. 

This master should act as an inhibitive master for only the yellow channels (those under control of a submaster).

It should not affect any values coming from other targets than submasters.

This could be useful if someone is busking but the set is recorded for television and there is need to limit the output of certain sets of light.

Also useful when you are controlling submasters from remote OSC and you need a way to temporarily disable this with a fade and also without switching off all OSC input.