People have absolutely no idea at the amount of respect that has to be there for a musician to even let someone else play his instrument, regardless of who that person is. And when someone DOES let you use an instrument the amount of care and respect that needs to be shown to it.

It would be one thing if there was an accident and Prince dropped the axe, but apologized and said he'd take care of it. But throwing a guitar while on stage isn't an accident, it's a purposeful act that showed complete disrespect to another musician that was so gracious to him in letting him use his axe.

I also want to point out, that Kirk may or may not have had a special connection to that guitar. I don't know. I've have basses over the years that I really had a connection with and would have been completely heartbroken over something like this happening, and I've also had some basses that I looked at as a tool and as long as it was fixed/replaced I would be fine. A guitar/bass is an instrument made of wood and for some models, each instrument is going to have it's own unique voice that can't be replicated, while others (even some high end guitars) are very consistent in their build so a replacement will sound and feel exactly the same. But when you're borrowing someone else's instrument you should treat it with the highest level of respect regardless.