bug#20538: 24.4; Attempt to delete a surrogate minibuffer frame

["Roland Winkler" <winkler@gnu.org>]

I do not know how I got into this (sorry, I do not have a recipe to
reproduce this either).  I have a frame I want to delete by running
delete-frame.  Yet this only gives me the error message

  "Attempt to delete a surrogate minibuffer frame"

and delete-frame refuses to do its job.  What does this mean?  If
nothing else, Emacs could do a better job explaining to the user
what it believes is going on and how the user can possibly resolve
this.

Possibly a relevant detail: I like to run Ediff sessions with one
split frame showing both buffers I need to compare.  Yet Ediff
sometimes comes up with its own ideas about resources it likes to
use, grabbing another frame to show each buffer in a separate frame.
If I remember correctly this happened here, too, that is, maybe
Emacs believes that the frame I want to delete was/is part of the
Ediff session.

PS: Neither the Emacs nor the Elisp manual mention "surrogate" in
any context.




In GNU Emacs 24.4.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.4.2)
 of 2014-10-26 on regnitz
Windowing system distributor `The X.Org Foundation', version 11.0.11103000
System Description:	Ubuntu 12.04.5 LTS

Important settings:
  value of $LC_COLLATE: C
  value of $LANG: en_US.ISO-8859-15
  locale-coding-system: iso-latin-9-unix