From this page, I find that the impact strength of polycarbonate bulletproof glass is 850 Newtons. That means that, to shatter the glass, the thrower would have to impart 635 m/s^2 of accelleration on the metal - that's, like, 63 G's. This isn't taking in to account impact area, of course, but it's pretty clear to me that the glass won't shatter.

If the glass doesn't shatter, then the energy of collision will have to be dissipated somehow. I think the metal would indeed bounce back, but as some energy will be absorbed by the material (ie, it's not a perfectly elastic collision), it will not hit the thrower in the head unless she somehow moved both closer to the glass and lower to the ground.

So, if she threw it so hard that she fell over towards the glass then it could plausibly hit her.

Part of it depends on whether the collision is elastic or not.

From a freshman physics point of view, energy could go to (1) sound (2) vibrating the glass (3) deforming the metal, (4) heat, and (5) so on, all of which would then lessen the amount of energy which would go into the velocity of the metal bouncing back.

Elastic collisions theoretically have none of 1-5, and just about all real-world collisions are non-elastic to some extent. It's a matter of how non-elastic though.

I think....what you're really asking with this question, The Whelk, is, "I would very much enjoy a hug and perhaps a cookie if one were handy?", perhaps punctuated with a please and thank you for Mommy?

There, there.