opening screensavers in QC is everybody’s routine task, you can imagine. so turns out you can do it by just option-clicking the “Screen Saver options…” button in the Screen Saver preference pane. works for the stock savers too.
found in the manual. also, according to the manual’s writers,
And here’s an example of a music visualizer from within the Quartz Composer itself:
Boy were they having a good time at Apple in mid-2000’s.