I had a stuck window, and it would NOT open. The latch would pivot just fine, and if I looked very close I could see that the window would slide back and forth about 1 mm, but wouldn't open, which seemed really weird. It was as if something were obstructing the window, as you would expect a latch to, but the latch appears to disengage fully.
Today I verified that the glass slides up and down slightly in the track, as you would expect; it slides up and down at the rear, and even in the front, although it takes a bit more effort. So the window is free to move around. Yet it won't open.
I got it open, and here's how: I ran a length of cord (1/8" braid) underneath the pivoting latch. Both ends of the cord were attached to a handle (it just happened to be a folding knife, and this cord was the lanyard). I pulled, which also lifts the latch away from its engaged position. Nothing happened. I gave it a sharp tug, and it came open, neat as you please.
My theory is that part of the latch/handle casting (not the moving part...the part that's fixed to the glass) becomes jammed in the track if you slam the window. I slammed the window to see, and it got stuck again, but now I knew what to do.
So don't slam your windows, OK? If you do, find a length of sturdy (but not larger than 1/8" diameter cord, and a handle you can tug on hard.