I recently received a tantalizing email from a reader I’ve never met: Sam Henri-Gold.

Sam showed me how you can key in a couple write commands in the macOS terminal:

defaults write NSGlobalDomain WebKitDeveloperExtras -bool true
defaults write -g WebKitDeveloperExtras -bool YES

Which will enable a context menu in a system web view:

Which lets you trigger the Safari Web Inspector and inspect elements of the view — like you would any website:

I find this fascinating! I’m intrigued by the ability to use system colors in CSS and these web views in macOS show how engineers at Apple are leveraging non-standard CSS keywords in Webkit to mimic UIs in macOS which are otherwise built with native system APIs.

It’s kind of like opening the developer tools in an Electron app, except these are native macOS apps with web views parading as system UI.

I’ve poked around in the “Apple ID” and “Family Sharing” panes in the macOS System Preferences where I’ve spotted a few intriguing details.

For example, in the Apple Music tab of Family Sharing preferences I find a javascript-packed.js file