Design language

Regarding preferences being a separate window, it’s hard to list concrete situations where that’s useful, but there are a number of edge cases where having the Preferences panel being modal (and not actually a window) is insanely frustrating, because I remember running into them in several apps over the years.

Electron apps consist of 95%+ of the offenders in this category, but a handful of native apps have been guilty too. Two examples are Slack and iTunes/Music, where it’s useful to be able to have the two windows side-by-side so one can adjust options and play with the the resulting UI in the main window until it’s tuned to perfection. These apps have modal preferences, so you can’t do that and end up with a laborious “ping pong” effect bouncing between the preferences pane and the main window, since the main window is obscured and can’t be interacted with. It’s also just kind of a waste of a full-fat OS with a nice floating window manager — this is a desktop/laptop, a device made for power users, not a smartphone/tablet/chromebook.