* app/widgets/gimpitemtreeview.[ch]: Make instance member private
and add getter that didn't already exist.

(gimp_item_tree_view_get_new_button)
(gimp_item_tree_view_get_edit_button): New getters.

* app/actions/actions.c
* app/widgets/gimpvectorstreeview.c
* app/widgets/gimplayertreeview.c
* app/widgets/gimpdrawabletreeview.c
* app/widgets/gimpchanneltreeview.c: Use new getters.

svn path=/trunk/; revision=27827