This signal is emitted either when an object or interface is added or removed a when property has changed.
Additionally, multiple received signals are coalesced into a single signal that is rate-limited to fire at most every 100ms.
Note that calling settle will cause this signal to fire if any changes are outstanding.
For greater detail, connect to the object_added, object_removed, interface_added, interface_removed, interface_proxy_properties_changed and signals on the object_manager object.