you know, it would function like undo does in every other program created, and it actually undoes something.
I came here to post the same thing. I would love to have an Undo and a Redo button that works on all settings including environment, materials, etc.
Undo is coming - for everything. KeyShot 2.1 will have it.
And that's why we all love 2.1 already!!! ::)