Download the screensaver demo from the DarkGDK page at www.thegamecreators.com
Its a proper windows screen saver, made using darkGDK and dark physics.
As a proper screen saver it accesses the registry to write its options and things, I remember looking at that when I was doing this myself. There may be other examples, but thats the one I know off the top of my head that comes from a working app as such, so is probably close to an optimal way of doing it.
That screensaver is also great to look at for a number of different things, completely besides the physics(which is handy aswell, its using quite a few darkphysics techniques) it is a GDK application that has NO window, it uses the screen saver tab thats part of the windows display properties applet to display its options and even itself in a preview window, you can see in the code how they achieved it, quite interesting. The media for it all us stored inside the EXE using a program called molebox, which is another nice technique to look at if you need something like that.
Its quite a showcase of intermediate to advanced GDK techniques i've found.
If it ain't broke.... DONT FIX IT !!!