There was a utility called "WindowShade X" which (messily) hacked the functionality back into early versions of Mac OS X. This developer's utilities had a nasty habit of breaking with every OS update, though, sometimes even making the machine fail to boot, so it probably comes as no surprise that it's no longer available.

The same developers also had a UI skinning utility called ShapeShifter, which is probably what you're getting WindowShade X confused with.