lock phone keys

is it possible to lock all the phone keys in a windows phone 7 app (silverlight or xna)?

I need to create an app for toddlers and it would be great to开发者_C百科 lock all the keys so only adult can exit from app

It is not possible to lock the main keys of the phone e.g. Start, Back, Search - the Back button is overridable but must only be used to dismiss a dialog or go to the previous screen - any other behaviour is not allowed and is enforced by Marketplace Submission criteria.

I think you're looking at the wrong platform for your target audience. Why not develop an Xbox 360 game?