bug#53745: Toggle the visibility state of frames

[Kevin Vigouroux via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

One could say that it’s not that obvious! At first sight, I don’t see
much point in making a frame invisible.

`make-frame-invisible' is a special command only mentionned in the Emacs
Lisp Ref. manual. The user must be able to select the frame again to
make it reappear using `make-frame-visible'. It is not clear if it is
possible to run `make-frame-visible' interactively (as a command).

So far, the only reference I have found about this topic is
`minibuffer-exit'.

#+begin_quote
`minibuffer-exit'

When this parameter is non-‘nil’, Emacs will by default make this frame
invisible whenever the minibuffer (see Minibuffers) is exited.
Alternatively, it can specify the functions ‘iconify-frame’ and
‘delete-frame’. This parameter is useful to make a child frame disappear
automatically (similar to how Emacs deals with a window) when exiting
the minibuffer.
#+end_quote
-- 
Kevin Vigouroux
Best regards