The OnBackButtonClicked event is available for all pages (top pages and sub pages). In the solution display and in simulations, the Back button is located at the top left of the screen.
The default behavior of the Back button depends on the page type:
•Top pages: A prompt appears asking whether you wish to exit the solution. Click Yes to exit, No to cancel.
•Sub pages: The display switches to the previous page, which would typically be the top-level page that loaded the sub page.
Defining a set of actions for this event overrides the default behavior listed above. Only the defined event actions are executed when the user taps/clicks the Back button.