What is the ButtonBarLayout and how should we use it?

Question

When I developed, I found a new widget called android.support.v7.widget.ButtonBarLayout unexpectedly. I tried to search it on the internet, but nothing was found, e

Answer 1

Regarding your question:
How should we use it?

I guess it is undocumented because it is not stable yet.
It just popped up because this long lasting complaint originate from poor ROM modification by device vendor.
https://code.google.com/p/android/issues/detail?id=78377

See #270 for the resolution regarding classpath and why all classes inside .internal. were made public. And nope even that fix a lot of bugs from poor ROM modification are still out there (in lots of device of well known brands). The issue is soon declined by project member.

I don't think we should use it just yet until the document show up.
Just my $.02 though.