What's new in at-spi2-atk 2.3.3:

* Fix for BGO#664822 - gnome-shell crash when an AT is launched

* Fix a reference leak if a child-added signal has no object value.

* Change a : to a / in the suffix to an event, to allow DBus match rules
  using arg0path.

* Only deregister objects when they are marked defunct, not when a previously
  defunct object is marked as no longer defunct.