commit 80e9ac12529016a69926dfdc0b1ff6cf619a0751
Author: Eric Abrahamsen <eric@ericabrahamsen.net>
Date:   Sun Apr 21 11:04:20 2019 -0700

    WIP on making Gnus windows atomic

diff --git a/lisp/gnus/gnus-win.el b/lisp/gnus/gnus-win.el
index 5f7154c545..d30c8b84ad 100644
--- a/lisp/gnus/gnus-win.el
+++ b/lisp/gnus/gnus-win.el
@@ -38,6 +38,10 @@ gnus-use-full-window
   :group 'gnus-windows
   :type 'boolean)
 
+(defcustom gnus-use-atomic-windows t
+  "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
@@ -401,6 +405,15 @@ 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-let ((parent (window-parent (selected-window))))
+	  (when (window-parameter parent 'window-atom)
+	    (walk-window-subtree
+	     (lambda (win)
+	       (set-window-parameter win 'window-atom nil))
+	     parent t)))
+
         ;; Either remove all windows or just remove all Gnus windows.
         (let ((frame (selected-frame)))
           (unwind-protect
@@ -422,6 +435,13 @@ gnus-configure-windows
           (set-buffer nntp-server-buffer)
           (gnus-configure-frame split)
           (run-hooks 'gnus-configure-windows-hook)
+
+	  ;; If we're using atomic windows, and the current frame has
+	  ;; multiple windows, make them atomic.
+	  (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)))))))))