SplineEQ undo/redo, A/B

[A_SN]

I'm working on an undo/redo function as well as A/B comparison (or more than just A and B) for SplineEQ after realising how important it would be to the workflow, but I'm not sure how to do it on the interface. Do you have any favourite method from other plugins?

Also I think I should make a function to turn a curve that uses non-default "Curve effects" into the exact same curve but with no curve effects, because otherwise you can be limited in how far you can push your points. But I'm not sure either how I should do it on the interface. A big round button like the preset buttons? I have mixed feelings about those already. Slimer buttons? A sort of menu?

All of those things kind of clash with the rest of the interface being all knobs and I'm not sure what to do about it.