When I create a class that inherits from Page, I get different verification behaviors depending on whether I explicitly write the code to create elements, or if I use the new declarative, attribute-driven syntax. If I write a declarative-style property for an element, using that element does not perform document verification (Url, IsSecure, etc.), whereas, if I explicitly write the code to get the element ala Document.Button, then the Url and other document properties are verified. I would expect that Document verification to occur even when I am using the declarative syntax - otherwise, it's possible that the verification would never actually be performed, unless I explicitly access the page's Document property prior to doing anything with the page. I have included a file that demonstrates this variation in behavior.
Variation in document verification between explicitly-coded element property and declarative attribute-style property.