The next call to gtk_list_box_get_selection_mode just expected the GtkListBoxRow's parent to be a GtkListBox and failed when the row was added to something other than a GtkListBox. https://bugzilla.gnome.org/show_bug.cgi?id=733782
The listbox row accessible code was giving warnings when parent is NULL, at destruction time.
Now that multi selection is supported, we can provide a more complete AtkSelection implementation.
This lets us do two things: 1. Set the list-item role 2. Set selectable and selected states as appropriate https://bugzilla.gnome.org/show_bug.cgi?id=692258
