On BlackBerry 10 devices, peeking feature is when an app is moved aside, causing the app to transition from a full screen state to the invisible state directly.
The peeking feature is the ability to see behind a card using a gesture to drag the card off the screen to expose the card's parent or root.
The events passed when an app is “peeked aside” are:
The following diagram shows the events that are received when the app is peeked: 
Your code needs to handle the reception of each of the above events and properly respond to each of them. For more information regarding each of these events, see Various States and BPS Navigator Events sections.