* lisp/frame.el (delete-other-frames): Add universal prefix `iconify` arg

(frame--current-backround-mode): New function,
extracted from `frame-set-background-mode`.  Use `color-dark-p`.
(frame-set-background-mode): Use it.
3 jobs for master in 18 minutes and 36 seconds (queued for 4 seconds)
Status Job ID Name Coverage
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passed #16942
test-fast-inotify

00:08:32

 
  Normal
passed #16943
test-lisp-inotify

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passed #16944
test-lisp-net-inotify

00:10:03