Allow "soft-disable" for styles (keeping inheritance without actually displaying)

Say you have Style B, which inherits from Style A (prosilver).

If you want to use Style B, Style A needs to be active.

But maybe you don't want users to be able to select Style A. You only want Style B to be usable on your board. Currently this is not possible, because Style A always needs to be active in order for Style B to work.

"Override user style" would work in this case, because we only have 2 styles. But if you have Style C, D, E and F, but only want to "disable" Style A... you're out of luck.

I propose a new Style property. Something like "visible", "user selectable" or (inverted) "soft-disable", or something along those lines.