@albertopq This is where I really need some help.. you are right, when I return false, its not allowing the cancellation of the activity.
But when I returned true, I was facing issues in displaying the activity inline.. here is the code which calls the "update" activity:
https://github.com/ssaroha/gaia/blob/7979fc79483e76259947720fef5f03c8450a3e0e/shared/js/contact_dialog.js#L144

What's the best way to achieve inline update, with ability to cancel.