New XForm appearance: hierarchy-visible groups

[Xiphware]

@cooperka

It doesn't look like you can set multiple appearances on a single node,

I dont know about group appearances, but you can have multiple space-separated appearances on controls; eg select

@cooperka

To solve this you'd simply need to nest the groups -- an outer toc-visible group and an inner field-list group.

That rather seems like a potential candidate for supporting multi appearacnes for groups: ie "field-list toc-visible" ?