I've installed fireflies screensaver from X11:Utilities/openSUSE_11.3
And it even wasn't shown in KDE screensaver list. OK, I've made .desktop file for it in /usr/share/kde4/services/ScreenSavers/

Code:
[Desktop Entry]
X-SuSE-translate=true
Exec=fireflies
Icon=kscreensaver
Type=Service
X-KDE-ServiceTypes=ScreenSaver
TryExec=/usr/lib/xscreensaver/fireflies
Actions=InWindow;Root;Setup;
X-KDE-Category=OpenGL Screen Savers
X-KDE-Type=OpenGL
Name=Fireflies

[Desktop Action Setup]
Exec=kxsconfig fireflies
Name=Setup...

[Desktop Action InWindow]
Exec=kxsrun fireflies -- -window-id %w
Name=Display in Specified Window
NoDisplay=true

[Desktop Action Root]
Exec=kxsrun fireflies -- --root
Name=Display in Root Window
NoDisplay=true
Now it can be seen in KDE screensaver list. Moreover both "Setup" and "Test" buttons works. I.e. when I press "Setup" screensaver configuration dialog is shown, and when I press "Test" screensaver is started fullscreen, as expected. The problem is when the screensaver is auto-started after specified time-out only black screen is shown. What the catch?