I kind of thought this would have been there with the new mixer undo but apparently not, so hence this FR.
I would imagine this to work similarly in both Mixer undo history and Edit History Dialog.
As it is at the moment you have an undo list - last in-first out. This is basically like hitting Ctrl-Z multiple times. What I would like to have is the ability to undo something in the middle of the list, leaving the last actions untouched.