ok, so this should have been easy for me but for some reason it took a half hour to figure it out so I figure it must be something that some one else might struggle just in case. That being the case if you are in some nested set of user controls and need to get a reference to the top level of your phone 7 UI here is the code:
PhoneApplicationFrame Temp = Application.Current.RootVisual as PhoneApplicationFrame;
MainPage TheUI = Temp.Content as MainPage;
now main page is the loaded PhoneApplicationPage is this could change pending your code and further 'TheUI' is something I made up but all things the same the reference to TheUI would then allow you to call any instances of the root visual. and the best part is this is admittedly a bit hacky... :)
PhoneApplicationFrame Temp = Application.Current.RootVisual as PhoneApplicationFrame;
MainPage TheUI = Temp.Content as MainPage;
now main page is the loaded PhoneApplicationPage is this could change pending your code and further 'TheUI' is something I made up but all things the same the reference to TheUI would then allow you to call any instances of the root visual. and the best part is this is admittedly a bit hacky... :)