What I think goMac is trying to say is something like this: ShapeShifter is acting like a secret agent who infiltrates your office and replaces your files every time you go to look at them. He doesn't actually go into your filing cabinet and physically alter your files and folders, but when you pull something out to look at it, he rappels down from the ceiling Mission Impossible style and does a quick switch on whatever you're about to look at.

(Yeah, yeah, we've heard it before.)

But even when you're going into Search.bundle to find those resource images, ShapeShifter is still doing it's job. Whenever you try to look at them, ShapeShifter performs its little switcharoo. It doesn't matter whether the images are being displayed in the window of an application or if they're being opened in Preview.