Re: What are invisible frames for?

[Stefan Monnier <monnier@iro.umontreal.ca>]

> I know that "emacs --daemon" creates a frame that isn't displayed.  I
> don't know if that frame is an "invisible frame" by this definition, but
> I thought I'd mention it, just in case.

No, that frame is yet different: it's "visible" but it's in a "dummy
terminal" not connected to any GUI and not even a tty (it's initially
connected to the stdin/stdout, tho, so `message` gets output to stdout,
for example.  It's the same dummy terminal that's used when Emacs runs
in batch mode).

BTW there are yet more forms of "invisible" frames: those frames that
are displayed on terminals that the user cannot currently see
(e.g. connected to a $DISPLAY that's in a different physical location).

This is relevant in the sense that when a minibuffer is on a frame
that's connected to display to which the user doesn't currently have
access, it can make Emacs unusable.  For this reason, `server.el` calls
`top-level` sometimes.


        Stefan