I expected to stop into the glass, go to the stairs(down) and at the plesureplate.
It should jump infinity at the stairs(how was hapened somes times).

Some times when you shot with a dispencer at a glass pane the block with you shot will go over the glass.

Steps to Reproduce:
1. Put a dispencer and power it somehow.
2. In front of it put a glass pane wall.
3. In the dispenser put items(I put minecarts with MCedit becauze the minecarts are don't stock and I can show what happens evry shot).
4. Shoot with despenser several times and the block will go over the glass.

I take a video when I discover it: http://www.youtube.com/watch?v=NxZYszRRoaI&feature=youtu.be