Does anyone have a small demo that shows the "Group" constraint doing what it does?

update...

I got it to work when i create one in the Chor, but not in a pose.

How does it work? What does it do?

it attaches a bone to any group. So the bone follows CPs instead of CPs following a bone.

The original description published with this had that backwards.

It is a translation only constraint, AFAIK, no rotation.

Pinning a button to a cloth sleeve could use this but still needs something to deal with orientation.