Problems using xfce on xubuntu 11.04 due to Ubuntu's move to Unity desktop

[Chris Green]

I'm having lots of problems having just upgraded to xubuntu 11.04
because of the Unity desktop that Ubuntu now uses.

I have just hit the *fourth* program which has lost its menu bar because
it thinks that there's a Unity desktop with the menus there.  So far the
programs affected are Firefox, VirtualBox, Wammu and another.

Firefox is fixable by disabling a plugin but I can't find any way to get
the menus back on VirtualBox and Wammu.

Can anyone suggest a way around this problem?

-- 
Chris Green