Is it possible to configure a multi-site EPiServer install that doesn't require the user to re-authenticate when moving from site to site in Edit Mode?and user is loosing unsaved & published data.

The problem is that Edit Mode runs under the domain name of the site of the page you're viewing.  So, if you move from a page on Site A to a page on Site B.  You have to login again.

Sure, you only have to do this once per browser session, but my client will have 6 Web sites.  It's a problem.

How can I configure Edit Mode to stay on the same domain, no matter what site the currently-viewed page belongs to.