title: dbus how to reconnect to a new session bus daemon
body: <p>As far as I understand it, a dbus user connects to the session bus daemon if the environment defines two variables like: </p>
  
  <pre><code>DBUS_SESSION_BUS_ADDRESS=unix:abstract=/tmp/dbus-1cAnv4I,guid=3a453c40b5034f
  DBUS_SESSION_BUS_PID=102
  </code></pre>
  
  <p>If the daemon stops and we start a new daemon by dbus-launch, we will get new values for the environment. In this case how the new values can be propagated into a running user process without restart? </p>