Discrete action undo

[ivelieu]

When I press ctrl-z for undo, I expect it to undo up to the last time I pressed a button. But if I click and drag to move a transform in the preview window, for example, the ctrl-z undo buffer seems to save lots of increments up to the point. It seems to only be an issue when moving moving things in the preview window. I can't tell if this is "it's a feature, not a bug" kind of thing, but it's very impractical. It gets worse because the preview re-renders after every ctrl-z rewind, which makes rewinding before a single button press tedious, especially when I want to try and smoothly line up start and end keyframes.