Thanks to commenter Wellington at omgubuntu.co.uk in this post
[link] I was lead to a firefox extension by
Javier S. Pedro [link] that makes the browser menus work with gnome2-globalmenu
[link] I've only tested this on Firefox 3.6, on Ubuntu 10.10 and Linux Mint 10. No guarantees whatsoever that this will work on your system

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XPI DOWNLOAD (32 bit)[link]XPI DOWNLOAD (64 bit)[link]INSTALLING FROM SOURCEThanks to carlosdark54 for solving the libxul dependency problem on ubuntu. Just install the xulrunner-dev package:
"sudo apt-get install xulrunner-dev" or find it in the Software Center.
Then install git. Open up a Terminal window and type in:
"sudo apt-get install git" without the quotes.
Then type in "git clone git://gitorious.org/firefox-gnome-globalmenu/firefox-gnome-globalmenu.git".
Change to the directory where you downloaded the folder:
"cd /home/YOURUSERNAME/firefox-gnome-globalmenu".
Then type in "make -C src dist". There should be a globalmenu.xpi file in this directory. To install it, click on File in firefox, select "Open File" and navigate to where you compiled the globalmenu.xpi file. Select this file, and install it.
thanks
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what themes on your ff?
[link]