Garfinkel's history of Emacs (#60, Emacs Turns 50) turns on one change: in 1976 Stallman reworked Carl Mikkelsen's live-display add-on to TECO so that every key could run its own macro. The editor became a place where you rewrote the editor while using it.

Hanacek's dyna.ink (#55) asks for something similar from a canvas: you draw, it reads your drawing back, and you accept or challenge the reading. Both put the tool's interpretation inside the loop instead of behind a menu.

Engelbart's 1968 demo (#5) is the common ancestor. Try it: pick one thing your tool does on its own, a template or autocomplete, and find out whether you can change it without leaving the work.

Dynamicland (#8, Bret Victor and team) puts programs on paper in a shared room. Chalktalk (#26, Perlin, He and Rosenberg) puts them on a drawn glyph that you click to run. Both make code something you point at, not something you open.

The difference worth testing is who can reach in. In a room, anyone standing there can move a page. In Chalktalk, whoever holds the pen decides.

Try it: sketch one small simulation on paper, a ball and a wall, and hand the paper to someone else. Note where they reach first, and what they change without asking.

Chalktalk (#26) turns a drawn glyph into a live sketch you can link to other sketches: its binary tree takes a swipe to undo and a drawn curve to trigger a traversal. Crosscut (#23) starts from the same instinct, a stylus on a page that keeps the looseness of paper and gains the behavior of a model.

The Chalktalk paper is candid about what is missing: no formal evaluation, a stack and a tree that cannot yet call each other, a link type system still in research. That candor is the useful part.

Try it: draw a stack on paper and name two operations, push and pop. Then ask what a second drawing, a tree, would need to send the first for the two to explain a call stack together.