If you want to include the XDG menus (used in gnome) in your FVWM menu, have a look at Piotr ZieliÅski‘s fvwm-xdg-menu. You’ll need PyXDG to make it work.
BTW he has many other exiting things in his config, so check it out.
Personally I prefer to start my applications from a terminal, but it is useful for programs you don’t use very often. And a little cool 
