CentOS - Nov 2005 - auto hide gnome desktop TOP panel

I turned on the auto hide of the TOP panel on gnome desktop.
I does hide but I still see like 2 or 3 pixel lines of the panel???

How can I completely hide the top panel?

I tried change the number of pixels in the panel it always still shows
a couple pixel lines.

I have a dell inspiron 8200 laptop.

THanks, for any suggestions.

Jerry