Leslie Lamport uses Emacs (src1, src2)!
Here is what we know about his setup:
- os: Windows 11 - dark system, light applications
 - Emacs with 
light-bluetheme - Latex in a message buffer
 - sumatrapdf - PDF reader for Windows (I am sponsoring Krzysztof Kowalczyk via GitHub)
 - TLA+toolbox
 
Presumably his .emacs file may look something like this:
(custom-set-variables
 '(column-number-mode t)
 '(custom-enabled-themes '(light-blue))
 '(tool-bar-mode nil))
(menu-bar-mode 1)
(toggle-scroll-bar 1)
(tool-bar-mode -1)
(column-number-mode 1)
Links
- Deconstructing the Bakery to Build a Distributed State Machine
 - Leslie Lamport: “…the best medium is hypertext…” + “we should get rid of our 17th century habit of writing on dead trees.
PDF was designed for printing, and cannot do hypertext…” (src) 
As it turns out the light-blue theme may no longer be available in Emacs 29.1+
⛔ Warning (initialization): The `light-blue' theme is obsolete since Emacs 29.1
Someone else ran into this too:
- https://www.reddit.com/r/emacs/comments/15xv71w/my_favorite_theme_lightbluetheme_was_obsoleted_in/
- There is a discussion in emacs-devel@gnu.org on “Why has the light blue theme been made obsolete?”
 - bug report
 
 
Speaking of Windows…
Windows 98 was my favorite.
(src)Happy to find out that DOSBox-X is an active project and available for many platforms.
Install on macOS is as simple as brew install dosbox-x.
DOSBox-X runs on ChromeOS too!


