lol. Nate, I found a bug.
Remember I was scaling bones down to 0.0 to hide their child bones and images? I was doing it to hide limbs temporarily while setting up. And Spine kept crashing at the same point for some reason.
It turns out, it crashes when I drag a slot into a bone that's scaled to 0. My suspicion is that there just might be a division/multiplication involving zero in the compensation code that gets applied when you parent something that's causing it to crash.
I'd call this a funny, low-priority thing, 'cause who in their right mind would parent an image to a bone scaled to 0, right? But there you go. : p