How to customize the sorting separator in a visual style

In Windows 7, I want to change the look of this black separator that shows up when sorting items.

It still uses Windows 2000 visuals! I can't allow that. Drag something to a different position and you may see the black separator. In Windows 7, the sorting feature has been removed, but I used some hack (most likely from this forum) to get it to partially work on Explorer, which is why I can move the folders as shown above. It's also on the Start menu, but I don't care for it there one bit.

I know how and use Vista Style Builder. It's simple. But I don't find this anywhere. I went through every single resource and didn't find a picture that looked like this separator in the visual style theme files. That's a good hint that this can't be changed. It's got to be located somewhere in some file. Where?

It's something for @Bongo to answer. :)