If you've created a Diazo theme but don't (yet) have the time to make it work nicely with Plone's logged in user interface (e.g. for editing and managing content), you can use this somewhat dirty trick: disable the Diazo theme for anyone logged into your site.
This works if your site doesn't require users to log in to view content such as Intranet-like, password-protected areas of the site. The assumption is that the only people logging into your site will be content creators, editors, and site administrators.
To disable a Diazo theme for logged in users, add this rule to your rules.xml:
If, however, your site requires that users log in to view password-protected content, you probably want those users to still see lovely theme you've created, and you want users with Manager role to see the unthemed Plone UI.
If you want logged in users to still see the themed site but you want Managers to see the unthemed site, use this rule: