This segments privileges more, making it so that any app connecting to wsys.sock can't just always access every single advanced feature in wind if they don't need to.
Of course, apps have to restrict themselves, which is why only privileged apps have access to this feature in the first place.
Normal apps' pledges are all empty and can't be changed.
An example: taskbar uses the "ExtendedLayers" pledge to move its window to the background, but relinquishes it afterwards, and doesn't need any other advanced feature for now.
If a pledge-capable app tries to use a pledge-protected function without having pledged anything, it can't. Pledges are mandatory if you want to access certain functionality, unlike the kernel's pledges which make every syscall available if you don't use pledge().
Two layers are accessible to all apps: global and global_top (for popups and similar windows).
Three other layers are accessible to privileged clients (background, system and lock), for things that need to be on a different level than user apps, like the taskbar, system popups, menus and the lock screen.
Whenever a GUI session ends, SIGHUP is sent to all GUI processes. Previously, taskbar would catch this signal and wrongly restart.
Now, taskbar correctly dies alongside everyone else.
Why are command-line utilities stored in "apps"?
And why are apps like "editor" or "terminal" top-level directories?
Command-line utilities now go in "utils".
GUI stuff now goes in "gui".
This includes: libui -> gui/libui, wind -> gui/wind, GUI apps -> gui/apps, editor&terminal -> gui/apps...
System services go in "system".
