I tried creating an entry with a behavior that only allowed integers to be entered. I handled the TextChanged event and if the entered value wasn't an integer I'd set the text back to the old value. The text would never change back in a windows store app (It did work for a windows phone app). I had an object databound to the control and it's value changed correctly but the Entry would still display the invalid characters.
Related to this I have a form that allows saving and adding a new entry. After saving I remove the databinding from all of the form's controls and rebind a new blank object. All controls are reset except for the Editor control. Even if I directly set the text field to null the Editor's text value will not change.
In both instances I can step through and see the new value being assigned but after I step past the assignment and look back at the control it's Text field was not changed. There must be something in the setter that is ignoring my change. I tried removing databinding to see if that was affecting it but it behaved the same.
Again this all worked perfectly for windows phone. The only problem seems to be in the implementation for Windows Store apps.