Missing icon on the system tray or notification area after switching to a different user (fast user switching).

Here is the scenario:

user1 freshly login from a newly cold-booted system.
 Network-Manager work as normal.

user1 switch to user2 account
 Network-Manager icon missing on the system tray or notification area

now, user1 want to closed or logout totally the backgrounded session.

user2 would login back on the GDM to open his previous session.
 There is no way to see or control the status of the Network-Manager on this session.