Notebook: Jupyter's look and ergonomics

Code cells in boxes with [n]: and Out[n]: prompts and a ▶ that runs
them; notes drawn as text, in a box only while edited; a bar by the
active cell, blue in command mode and green in edit mode (▌, ▎ for the
other cells selected, a heavy box while edited, so it reads without
color). A toolbar where the formula bar is: run, stop, restart, run
all, add, cut, copy, paste, the cell's kind, and nu's status, clicked or
keyed, with chips where they fit; the context line closes it off as a
rule.

Several cells selected with Shift+Up and Down (J, K, Shift+click) run,
delete, copy, cut, move (Alt+Up and Down, Ctrl+Shift+Up and Down) and
change kind together; V pastes above. Outputs scroll in a window of
their own (arrows, the wheel), O shows them whole, o folds them, and
Clear output clears one. Go to cell (Ctrl+G) and a table of contents
from the notes' headings (View menu). Clicks select, edit where they
land, run, fold and open; right-click opens the cell menu. Run all
scrolls to each cell as it runs.

A mouse action's command is no longer dropped by Update.

commit

275c3f2fdd2c177e9234bf1bd0a1b5f05b056c6f

parent

89ca25dd4e0ee089e709d2b9a2d7e31f9a87bd80

author

Dami <dami.etoile@gmail.com>

kind

feat risk score 2.4 of 3, Jev's estimate