I work with at a company that manufactures glass shower doors. If people are not careful it breaks quite easily. We also get calls from time to time about glass "spontaneously shattering", however true that may be. If it breaks in a frame or in your hands, a lot of times it will make a loud popping sound and explode everywhere. I have never gotten a call about it shattering and staying together in frame. Not to say it can't happen, but I feel it would be more likely with an untemped piece breaking into large sections to stay together.