NMDevice @nmdevice: the object which received the signal. @arg1: @arg2: @arg3: @parent: @state_changed: @_reserved1: @_reserved2: @_reserved3: @_reserved4: @_reserved5: @_reserved6: @connection: @path: @Returns: @device: @Returns: @device: @Returns: @device: @Returns: @device: @Returns: @device: @Returns: @device: @Returns: @device: @Returns: @device: @Returns: @device: @Returns: @device: @Returns: @device: @Returns: @device: @Returns: @device: @Returns: @device: @Returns: @device: @error: @user_data: @device: @callback: @user_data: