[CentOS] topbanel and bottompanel on gnome

I am doing the following commands to "hide" the top and bottom panels on 
gnome.

       gconftool-2 -t int  --list-type int  --set 
/apps/panel/toplevels/top_panel/auto_hide_size 0
        gconftool-2 -t bool --list-type bool --set 
/apps/panel/toplevels/top_panel/auto_hide true
        gconftool-2 -t int  --list-type int  --set 
/apps/panel/toplevels/bottom_panel/auto_hide_size 0
        gconftool-2 -t bool --list-type bool --set 
/apps/panel/toplevels/bottom_panel/auto_hide true

When I do this I still see 1 pixel worth of panel after it hides.

How do I get rid of that 1 pixel (it looks like a line at the top and 
bottom of my screen).

Or better yet how do I completely disable the top and bottom panels 
using gconftool-2?

Thanks,

Jerry