Re: Question about üarent-frame changes

[Eli Zaretskii <eliz@gnu.org>]

> From: Po Lu <luangruo@yahoo.com>
> Cc: martin rudalics <rudalics@gmx.at>,  gerd.moellmann@gmail.com,
>   emacs-devel@gnu.org
> Date: Thu, 19 Sep 2024 16:41:24 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> Date: Thu, 19 Sep 2024 10:10:11 +0200
> >> Cc: gerd.moellmann@gmail.com, emacs-devel@gnu.org
> >> From: martin rudalics <rudalics@gmx.at>
> >> 
> >>  > sounds not very useful to me on a TTY, because switching frames on a
> >>  > TTY will make the child frame invisible anyway.  And why would I want
> >>  > to see a child of frame F1 when I display only frame F2?
> >> 
> >> Because the calling code may reparent the child frame from F1 to F2
> >> whenever the user switches from frame F1 to frame F2.  At least Po Lu
> >> said that applications do such reparenting.
> >
> > Isn't that the same as simply showing the child frame even though its
> > parent frame is obscured?
> >
> > And I'd need to hear more details about what the application wants to
> > achieve by such reparenting, to understand the issue.
> 
> They simply wish to retain created child frames for as long a period as
> possible, because frame creation is expensive, and configuring a child
> frame to behave as intended is hard work.  See posframe.el (on ELPA) for
> a typical instance, where three years ago I encountered the same dilemma
> with the Haiku port.

In what sense is creating and configuring a frame "expensive" and
"hard"?  Given that we have current-window-configuration and
set-window-configuration, I wouldn't expect it to be hard.