bug#35873: Add atomic window support to Gnus

[Eric Abrahamsen <eric@ericabrahamsen.net>]

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The attached patch adds atomic window support with a new customization
option, `gnus-use-atomic-windows', defaulting to nil. If t, a
multi-window Gnus layout will be treated as a single window when other
code pops up buffers. Ie, your completions buffer won't end up squished
between the summary and article buffers.

I'm pretty sure I've done the elisp manual cross reference incorrectly.

Thanks,
Eric




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From 48b94c157144230f9e955d4b94202ee152f3d820 Mon Sep 17 00:00:00 2001
From: Eric Abrahamsen <eric@ericabrahamsen.net>
Date: Thu, 23 May 2019 13:41:47 -0700
Subject: [PATCH] Add atomic window support to Gnus

* lisp/gnus/gnus-win.el (gnus-use-atomic-windows): New option
  governing behavior, default to nil.
  (gnus-configure-windows): Add and remove 'atomic-window parameter
  when switching window configurations.
* doc/misc/gnus.texi (Window Layout): Document.
---
 doc/misc/gnus.texi    |  6 ++++++
 lisp/gnus/gnus-win.el | 18 ++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/doc/misc/gnus.texi b/doc/misc/gnus.texi
index b9c91a02a3..c09d9dc47f 100644
--- a/doc/misc/gnus.texi
+++ b/doc/misc/gnus.texi
@@ -22918,6 +22918,12 @@ Window Layout
 to fiddle with @code{gnus-tree-minimize-window} to avoid having the
 windows resized.
 
+@vindex gnus-use-atomic-windows
+Lastly, when you've got a multiple-window layout, Gnus can treat them
+as one ``atomic window'' with regards to help or completion pop-up
+windows (@pxref{Atomic Windows, , Atomic Windows, elisp}).  Set @code{gnus-use-atomic-windows}
+to a non-@code{nil} value to enable this.
+
 @subsection Window Configuration Names
 
 Here's a list of most of the currently known window configurations,
diff --git a/lisp/gnus/gnus-win.el b/lisp/gnus/gnus-win.el
index 40c5b42d45..04d9e40884 100644
--- a/lisp/gnus/gnus-win.el
+++ b/lisp/gnus/gnus-win.el
@@ -39,6 +39,10 @@ gnus-use-full-window
   :group 'gnus-windows
   :type 'boolean)
 
+(defcustom gnus-use-atomic-windows nil
+  "If non-nil, Gnus' window compositions will be atomic."
+  :type 'boolean)
+
 (defcustom gnus-window-min-width 2
   "Minimum width of Gnus buffers."
   :group 'gnus-windows
@@ -402,6 +406,15 @@ gnus-configure-windows
         (unless (gnus-buffer-live-p nntp-server-buffer)
           (nnheader-init-server-buffer))
 
+	;; Remove all 'window-atom parameters, as we're going to blast
+	;; and recreate the window layout.
+	(when (window-parameter nil 'window-atom)
+	  (let ((root (window-atom-root)))
+	    (walk-window-subtree
+	     (lambda (win)
+	       (set-window-parameter win 'window-atom nil))
+	     root t)))
+
         ;; Either remove all windows or just remove all Gnus windows.
         (let ((frame (selected-frame)))
           (unwind-protect
@@ -423,6 +436,11 @@ gnus-configure-windows
           (set-buffer nntp-server-buffer)
           (gnus-configure-frame split)
           (run-hooks 'gnus-configure-windows-hook)
+
+	  (when (and gnus-use-atomic-windows
+		     (window-parent (selected-window)))
+	    (window-make-atom (window-parent (selected-window))))
+
           (when gnus-window-frame-focus
             (select-frame-set-input-focus
              (window-frame gnus-window-frame-focus)))))))))
-- 
2.21.0