Undo/redo in Adjust Curves

[Wixenia]

When using curves to adjust color reproduction. You can only undo the last set point. All others cannot be canceled, just discard the current one and start a new one.

https://user-images.githubusercontent.com/44490229/135636048-8701de9a-dac3-40aa-90bc-82fd895450da.mp4

[circular17]

There is no undo function yet. The button used here is to delete the selected point.

So possible improvement is implementing undo/redo.