This interface provides events that are triggered when specific user input events occur.
// Triggered when the hardware back button is pressed (Android only).
// Events are triggered in the reverse order in which they were registered.
// Pass true to stop propagation.
backButtonEvent: SubscribableEvent<() => boolean>();
// Triggered when a hardware key up/down event occurs. Events are triggered
// in the reverse order in which they were registered. Pass true to stop
// propagation.
keyDownEvent: SubscribableEvent<(e: Types.KeyboardEvent) => boolean>();
keyUpEvent: SubscribableEvent<(e: Types.KeyboardEvent) => boolean>();