Emitted when a signal from the remote object and interface that
proxy is for, has been received.
Since 2.72 this signal supports detailed connections. You can connect to the detailed signal `g-signal:
GDBusProxy:x` in order to
receive callbacks only when signal `x` is received from the remote object.
The sender of the signal or null if the connection is not a bus connection.
The name of the signal.
A Variant tuple with parameters for the signal.