Ouch, is that weed-eater damage? Do those two screws in the center of the window do anything? I would say that Francesca Knowles is probably correct and there are some springs holding the window centered side to side.
That does look like it's not a tempered window and that seems just plain foolish on the manufacturers part. I would second asking for tempered glass when it gets replaced. If you can get the slider out, take it to a residential glass and shower door place and let them figure out how to take it apart and replace the glass. I had to do that for a window in my trailer and it unfortunately wasn't cheap. ($250) but it's done and I'm happy now.