twosigma/beaker-notebook — pull request #606 by anglee (2014-09-10 19:00:14+00:00)
Title: Make delete cell undoable

After a cell is deleted, use Ctrl + z to undo. The history buffer size is 1. Also any other cell operation that involves recreating cell map, e.g. move up/down, will clear the history buffer and void undo.