Interesting. If I were walking in a parking lot with my little girl and noticed a car backing into our direction closely, I would slap the hell out of that car whether it was an accident or not.
I imagine anyone would in that situation. Getting into an discussion about who's getting a beating after the situation is an entirely different scenario, especially with a kid present. However losing my head with an adrenaline dump keeping my kid from getting run over...? No telling what I would do honestly.
The real question I have though is in regards to the idea of pulling your gun on a guy with a little girl in a parking lot. Regardless if glass was broken, fist were thrown, how does one pull on an unarmed man with a kid--unless they felt their life was in danger?
different if it were multiple attackers, he was armed, disparity of size, ect.