How do I get application menu on desktop right-click?

[Grant Edwards]

I just did a new Gentoo XFCE 4.6 install on a machine, and I can't
figure out how to get the application menu to appear when I right
click on the desktop (which seemed to be the default behavior on all
my other XFCE installs).  Instead of the application menu I get some
other menu with "Open in new window" and the top and "Applications >"
at the bottom.

Under the "Menus" tab in desktop settings there's a box labelled
"Show application menu on desktop right click", but checking or
unchecking that box makes no difference.

How do I enable applicatoin menu for desktop right click?

-- 
Grant