* app/widgets/gimpcontainertreeview.[ch]
(gimp_container_tree_view_set_dnd_drop_to_empty): New setter
function so that we can make the "gboolean dnd_drop_to_empty"
class instance member private.

* app/widgets/gimpcontainertreeview-private.h: Move member here.

* app/widgets/gimpcontainertreeview-dnd.c: Go through priv pointer.

* app/widgets/gimpitemtreeview.c (gimp_item_tree_view_init): Use
the new function.

svn path=/trunk/; revision=27671