Currently you can set the button captions or image but not get the button caption or image.
I fixed this too. Oh well…
Looks like the PlayBook and BB6/7 implementations are still outstanding. I've left a comment on the pull request. Feel free to collaborate with @1ap1 if you have those changes available.
final updates for issue #618
Checked in the updates for BB6/7/PlayBook buttons
Wiki has now been updated