My son tripped and fell into the back door and broke the glass. I was going to just replace the glass but I can't figure out how to insert it. Instead of being held in by removable moldings, it slides into a channel that 1/2" deep around all 4 sides of the window. So I think it would be impossible to simply slide in a new piece of glass without cutting the door apart. Does anyone have any ideas how I can repair this? I'm posting a picture of the window, and also a close up of the channel which runs around the perimeter of the glass.