>I assume "main page" means the 'normal' page that I would be using to see messages. If so, I don't see any option.
>If not, how do I access the page you mention?

The logout on the main page will not verify to close all existing windows which might have been opened. However, it does cancel the cookie. So, has you have discovered, if you switch to another opened window, it will no longer work. It is pretty much how it works elsewhere on the net. On some sites, I have multiple opened windows. When I do a logout, it will not close the other windows for me. One of the reason is that there is no way to make sure that the actual windows are in fact still on the Web site that the logout was done for.