Reduce font size. System > Preference > Appearance > Fonts, doesn't work

[Icarus Alive]

Hi,

Running Ubuntu 11.04 Desktop 32-bit, as guest, in VirtualBox 4.x
(64-bit). I've tried to reduce the font-size via:
System > Preference > Appearance > Fonts
i.e. everything to 8pt size.

and for many applications (for example the terminal window), this
change has taken effect. However unlike my 10.10 desktop setup (also
running in the same VirtualBox setup), where such a change reduced all
font sizes, in case of 11.04, I find that the font displayed for
gnome-panel (top & bottom), the application window title bar, are all
at the default font size. How can I change this ?

cheers,
Icarus