cannot start a xscreensaver screensaver with -root in KDE

[amdonati]

Hi,
I wanted to use a xscreensaver as background, but if I enter, for example /usr/lib/xscreensaver/atlantis, in the properties, the program is started in a window

If I add, -root, as was explained in an article I found, nothing happens!

What can I do to make these screensavers runnign as background?

Btw, I noticed that there is a xscreensaver.kss, but I cannot see this in the KDE screensavers list!

Thank you for the help

Adalberto