“Add a new toggle - whether to show local or recursive scale ducks. Not yet functional, but the status is updated. alt-8 to toggle, alt-9 for the 3-state.”
I guess they are for a previous implementation of bones and skeletons.
Apparently a bone stored its initial pose (setup): angle and scale, now they don’t.
Regular Skeleton Layers stores this info simply in animated value nodes (initial waypoint)
Skeleton Deformation layer stores each bone now as a bone pair, actually: the initial pose and animated pose. And to view the initial pose, user shall disable the layer.
“Show Bone Setup Handles” is grayed out, at least in the Synfig that I’m using, hence I’m unable to activate it. And the “next bone handle” did exactly the same what “recursive scale” did.