Why org.freedesktop.DBus.Local.Disconnected is called?

[Sheng Mao]

Sorry I missed some important information here. Please forgive me that I am not very familiar with field.

> However, I use busctl —user monitor org.kde.KWin, it seems org.freedesktop.DBus.Local.Disconnected 
> signal is issued, so the service is not unregistered.

The reason is I modified startkde to watch for unregistration of service org.kde.KWin, and after the unregistration, 
startkde should exit. However, I use busctl to monitor org.kde.KWin (busctl keeps running and waits for log messages), 
org.freedesktop.DBus.Local.Disconnected signal shows up in the log as the last message and busctl stops working.
Then I use busctl to check if org.kde.KWin still exits and the service actually disappears. But when I use 
QDBusConnectionInterface::isServiceRegistered to check if org.kde.KWin is still registered and the result is
the service still is registered.

So I am confused that why org.freedesktop.DBus.Local.Disconnected preempts unregistration and stops busctl monitor.

I am not sure if it is suitable to post it here. It is a dbus issue, a KDE issue, a Qt issue, and X issue. I am really confused.

Thank you!