The signal "property-change" is emitted when an object's property value changes.
arg1 contains an PropertyValues with the name and the new value of the
property whose value has changed. Note that, as with GObject notify, getting this signal does not guarantee that the value of the property has
actually changed; it may also be emitted when the setter of the property is called to reinstate the previous value.
Toolkit implementor note: ATK implementors should use notify_property
to emit property-changed notifications.
AtkObject::property-changed is needed by the implementation of
add_global_event_listener because GObject notify doesn't support emission
an PropertyValues containing the new value of the property which changed.