Can't change Facebook app site url?

Ok, so maybe I'm just going crazy, but did Facebook remove the option to edit the site url in their Developers application?

When I visit the overview of my apps (https://developers.facebook.com/apps/) and look at the summary of one of my older apps, I see the Site Url specified. When I then go to edit the app settings, there is no option to change the Site Url (in fact, it开发者_开发知识库's not even mentioned in one of the three tabs!).

What did Facebook do to it? A new app I'm trying to build is giving me a "Given URL is not allowed by the Application configuration." error.

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It's still there. There's more than three tabs.