What KDE sends to running programs when logout?

[bood]

Try this: http://doc.trolltech.com/4.2/session.html

Thanks, this helps a lot.
I reimplemented the QApplication::commitData function to save the data
Now the program can correctly save the data when logout
But the static object, which is used to make sure that there's only one instance of the program running, seems still not destroyed correctly.
Any suggestion?