Feature request: undo button

[robmarkcole]

As title, to go back and correct a bad annotation

[Tesax123]

This would be very helpful indeed, I was looking for this feature too!

[ashwaniyadav09]

An undo button would be helpful indeed.

Sometimes my Jupyter server isn't as fast and I click the button twice in a row before the text gets updated. I keep a note of all indices which need to be updated later, but an undo button would be a foolproof solution.

[vict0rsch]

Same :)