[triska]

For linear undo and undo branches, undo-tree.el is required:

https://www.emacswiki.org/emacs/UndoTree

Regarding "_", you can set up Emacs to treat _ as word constituent by modifying the syntax table. For example:

    (modify-syntax-entry ?_ "w")

For more information, please see:

https://www.gnu.org/software/emacs/manual/html_node/elisp/Sy...

[tom_mellior]

Awesome, thanks! I'll try these.