Whether the Back button hands control to the operating system instead of the application.
Only usable on Android or Universal Windows Platform (UWP). On all other platforms the property is a no-op: the getter always returns false and the setter has no effect.
The default value is false.
When the value is true, the operating system handles Back: it minimizes the application on Android and suspends it on UWP. Otherwise, the button is delivered to the application as the Escape key (KeyCode.Escape).