I had time to fix some existing bugs and here it is. The latest version includes scroll bars and progress bar.
It also includes an example theme image NuvoTheme, which you can see on these next few screenshots. It is a prototype like theme and serves as a testing ground for the theme maker.
Unfortunately installation of themes still requires root access, but I'm still hopefull that it can be improved even before OS 2006.
I also noticed that Opera doesn't use the same theme file as other programs do. For example the scroll bars are still the same in Opera even if you change them in your theme.
Download Theme Maker 0.4