I'm working through my first app, and have a simulated environment with image markers placed. Things seem to work OK, but I'm wondering – should the camera be able to lose track of the image marker once it is triggered? From what I'm seeing, an image marker, once found, is never lost, and never "deactivates". This prevents markers from "firing again". So, how does one, lose, and then re-trigger a simulated image marker? Should this be possible to simulate? Or more to the point, how do I make it so that my app can lose, and then re-trigger actual image markers when "re-found"?