GNU bug report logs - #45844
27.1; unwanted raising of other frame when emacs is in the backgound and switch-to-buffer is used in a dedicated frame

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From: martin rudalics <rudalics <at> gmx.at>
To: emacser <laszlomail <at> protonmail.com>, 45844 <at> debbugs.gnu.org
Subject: bug#45844: 27.1; unwanted raising of other frame when emacs is in the backgound and switch-to-buffer is used in a dedicated frame
Date: Wed, 13 Jan 2021 19:07:59 +0100

> (run-with-timer
> 3 nil
> (lambda ()
> (switch-to-buffer "*test*")))

You are asking for the impossible.  'switch-to-buffer' with a dedicated
window on an unsplittable frame will inevitably trigger 'pop-to-buffer'
as documented in the Elisp manual:

     Sometimes, the selected window may not be suitable for displaying
     the buffer.  This happens if the selected window is a minibuffer
     window, or if the selected window is strongly dedicated to its
     buffer (*note Dedicated Windows::).  In such cases, the command
     normally tries to display the buffer in some other window, by
     invoking ‘pop-to-buffer’ (see below).

And 'pop-to-buffer' makes a new frame because it cannot use the selected
one, raises that frame and even requests input focus for it.

I haven't much to recommend for how to handle such situations.  You can
try the following:

- Make an invisible frame when you start running the timer, maybe giving
  it a non-nil ‘no-focus-on-map’ parameter.

- Use 'display-buffer' to show *test* in that frame and make that frame
  visible, preferably using an 'inhibit-switch-frame' alist entry.

In either case it will be up to your WM whether it will raise that frame
and give it focus.  Often it does both, "stealing" another application's
focus.

martin

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