Add a class dialog

[thomaskole]

I would like to be able to add classes to objects in a similar way to how you would make it a target.

Just a simple popup box, type your classes, done.

I've managed to get some sort of proof-of-concept working by hacking it in, but it's not great.

Such a feature would be awesome :)

[k0a1a]

What's not great about your implementation?
Fork and let's see it ;)