Do a "netstat -a" after you shut down this app's interface AND task bar icon. Guess what? There you'll see this application still has a hidden connection to the Internet! Even after waiting a reasonable time, the hidden connection is still there. The only way to break the connection is to reboot your system!

Why is there hidden connection?
Why doesn't everything get shut down when the interfaces are shut down?
Why doesn't the hidden connection show up in the Task Manager or as a service?

This is no accident. This is intentional!