I bought a ipad mini and got a cover with it. 2 questions: a) When we open or close the cover, the ipad will switch on/off automatically. How does it work? Is there some kind of magnetic sensor? b) Here comes the inconvenience. Sometimes the ipad will not switch off after closing its cover. May due to some warping of the cover since its made of hard cardboard only and not a piece of stiff aluminium to ensure tightness when close. I have made it a point to manually switch off the ipad before closing the cover. Yet sometimes it will turn on by itself after awhile when the cover lid raise up a little. Is there a way to deactivate it?