Ability to undo or restore changes to the preferences #802

Is your feature request related to a problem? Please describe.
I sometimes experiment with making changes in the Preferences window, to see how the various options look/work, and I may forget to memorize or back up the previous settings prior to the changes, which then leads me to be unsure how to restore the previous state.

Describe the solution you'd like
It would be awesome if there was an "Undo" button (and maybe a "Redo" button as well?) in the Preferences window, similar to the Back/Forward history buttons in browsers, text editors, etc. This would allow reverting the last change done in the current view of the Preferences window. There's no need to persist a full log of changes after the Preferences window is closed (or even as one changes between tabs of the preferences window), but both additions would be welcome as well! :D

Describe alternatives you've considered
Maybe a way to restore each preference (individually) to its default setting would be nice too. But I'm not sure how that could be implemented without cluttering the UI.

Another option would be an additional button next to "Close" in the bottom right of the Preferences button, labeled "Close without saving", or "Discard changes", or something like that. This would undo all the changes made since the Preferences window was opened.