"Black glass borderless" it's minimalistic version of my "Black glass" style , without windows, tolbar and menu borders.
From version 0.9.11 Fluxbox doesn't support transparency defined in style config file, unfortunately.
If You want transparency like on the screenshot above, use alpha parameters:
- window: 200, menu: 180 (fluxbox menu>configure>transparency)
- toolbar: 200 (right click on toolbar).