Make a screensaver?

Does anyone know if there is a general method to making screensavers? I’ve seen some software packages that will turn flash movies into screensavers and such, but is it really that difficult?

What exactly is an .scr file that I can get it to work with different media-- or can I?

I think I read somewhere that a .scr is just an .exe with a different extension (although of course it has to have some sort of configuration thingy, which makes it a bit different)

You can change any file into a screen saver just by renaming it .scr

I have often made dos batch files into screen savers, and even .bmp files.

Oops. I just checked, and the bmp files were done by renaming a .com file that just displays whatever .bmp is in its parameter list. But again, it’s very simple.

How would you make a .com display an image? Are .com’s programmed in C++ or a windows language?

Well, it doesn’t work for Flash, at least. I tried it both with an .swf file (which did absolutely nothing) and the executable that one may expot flash files as (which gave me, mysteriously, a URL error for no reason at all).