Ubuntu – How to remove transparency from a GTK theme

I'm running Xubuntu 11.10 and I've got this here GTK theme which is pretty nice, and I like the title bars and everything, but I've got a problem.

Every menu in the entire system has this weird and annoying translucent effect. I don't want this effect.

I've pored through the gtkrc for the theme for hours now and turned up nothing, I've googled and googled, I've tried editing the pixmaps to remove the transparency but nothing I do makes any difference.

Each time I make any change, I reload the theme by changing it in xfce-appearance-settings and then changing it back. I have confirmed this does reload the theme properly by making other minor changes.

Does anyone know how I can remove the transparency from this theme?

Here's a pastebin of the gtkrc if it helps:
http://pastebin.com/QVa6LPZN

Pastebin of menubar.rc:
http://pastebin.com/S91cQ3T5

Pastebin of panel.rc:
http://pastebin.com/PQghvPUy

Dropbox of ~/.config/xfce4:
https://www.dropbox.com/s/b3vwcrohi0zdcb2/xfce4.tgz

Below is depicted a screenshot of the problem, demonstrated using a pop-up menu. Note that it applies to all menus – application menus, the main application menu and pop-up menus.
Background faded and image zoomed/cropped to highlight the issue, otherwise unedited

As you can see, the page behind the menu is visible through the menu – this is what I do not want.

How I installed it:

~/Downloads$ tar xzf 58426-Fawn.tar.gz
~/Downloads$ cp -R Fawn ~/.themes/

I then used xfce4-appearance-settings and selected Fawn from the menu.

I tried editing the pixmaps in ~/.themes/Fawn/gtk-2.0/Menu-Menubar/ and exploring the gtkrc in ~/.themes/Fawn/gtk-2.0/.