Comment 3 for bug 504169

My workaround:
- in gconf-editor, set /apps/panel/toplevels/top_panel/enable_buttons to 'true'; you can also do it in a shell like this:

    gconftool-2 --type bool --set /apps/panel/toplevels/top_panel/enable_buttons true

- now you'll get hiding handles on both sides; right-click on these to get the panel's context menu
- you can now hide the handles via the "Properties" option of the context menu, or in a shell with the above line, just use 'false' instead of 'true'.

In Lucid, you can access the menu, but the option "Add to Panel" will be grayed out. This is a consequence of how netbook defaults are implemented. See e.g.

https://help.ubuntu.com/community/UbuntuNetbookEdition/ConvertGnomeSession