get back to original value after sliding slider

Often after using a slider I just want to get back to the original value, especially if I'm just using the slider to explore what the value affects visually. But, by the time I stop sliding, I've lost the original value. The only way to get back is to do a ton of "control Z".

Would be nice to have a way to keep track of the original value and easily get back to it. And/or to see the diff and choose if I want the new or old value.

The issue names no files, tests, or entry points. Start by locating the browser slider interaction and how its value changes are tracked; then clarify whether the intended result is restoring the initial value, viewing a diff, or choosing between old and new values. Done should include an agreed interaction and coverage for the selected behavior.

Written by the indexing model from the issue text.