I used Urouhack for years under 3.0 & 3.1. It was a lot easier to set up than VisualPrefs (just create a directory, add a line to S:Startup-Sequence and forget about it) and it changed the window objects (scroll arrows, close box, front-back move, etc.) to very nice gradient XEN grayscale images. Unfortunately it seems this hack doesn't work with 3.9, which actually detects it and throws up a message "Urouhack sucks!..." etc.
Has anybody else seen this little cookie besides me?