Really great! I've been using it for a couple of days now. It feels really well-balanced and professional. My biggest concern with it is wheter it should be included in DockbarX theme package or in DockbarX itself. I guess you wouldn't mind either?
I have only two suggestions: - Make the button backgrounds transparent. In other words remove the background opaque layer from the button pictures (if you have worked with layers when you made them, otherwise this might be hard to do) so that your theme works with other backgrounds/dock themes. I hope you understand what I mean. - When multiple windows are opened the list to the right looks flat in comparison to the button, especially when a window of the group is selected.
That's because I'm using the wrong word. When you have say two firefox windows opened that's indicated with a small spline (hopefully that's a better word) at the right side of the button. That spline looks flat while rest of the button looks like it bulges out nicely.
This is just nit-picking, though. This is one of the best DockbarX themes I've seen. I seriously considered making it the next default theme of DockbarX but I realized it depends too much on the panel background to be suitable for that task.