Hi, I just made a new layout, as follows:
(http://i.imgur.com/zLsdIP6.png)
http://imgur.com/zLsdIP6
I'm also attaching the gtkrc that I'm using.
Copy sphink6.layout to ~/.config/gmusicbrowser/layouts and you can execute with:
GTK2_RC_FILES=gtkrc gmusicbrowser -layout sphink6