ScreenSaver

I have figured what the screensaver parameters are.
Preview is:
/p 2687732 (I do not know what these numbers mean so you might want to do Left())
Screensaver is:
/s
Settings are:
/c:2622250 (Again,I do not know what these numbers mean so you might want to do Left())

I guess they are handles, as you will need to interact with the chooser.

@ blitz programmer:
I programmed a little screensaver in C# and i want't to complete you list.
There are two situations:
1. Right Click on the *.scr file
/s for start
there is no preview
and no parameter for config

2. In the Screen Setup:
/s for start
/p for prieview
/c for config (ok it's c:"some nummbers")

Made a test utility which shows you with what parameters the utility is started. Get it from http://meissl.homeip.net/params.rar (coded in C#, so it requires the .Net Framework)

"Print commandline$():waitkey()" would do the job too.

For a Screensaver in Blitz, all you have to do is

if upper$(left$(commandline$(),2))<>"/S" then end

Of course, you can utilize the /C parameter too.

the c:<numbers> refer to a hWnd in C++ for the preview window on the screen saver, you need to do some API for that :)