[visual][popwin] add keybiding to resume last popwin buffer

bind it to `spc r w`

doc/DOCUMENTATION.org

@@ -143,6 +143,7 @@
       - [[#frame-manipulation-key-bindings][Frame manipulation key bindings]]
       - [[#emacs-and-spacemacs-files][Emacs and Spacemacs files]]
       - [[#browsing-files-in-completion-buffer][Browsing files in completion buffer]]
+      - [[#popup-buffers][Popup buffers]]
     - [[#ido][Ido]]
     - [[#ido-transient-state][Ido transient state]]
     - [[#bookmarks][Bookmarks]]
@@ -2594,6 +2595,11 @@ In =vim= style and =hybrid= style with the variable
 | ~C-k~       | go to next candidate              |
 | ~C-l~       | enter current directory           |
 
+**** Popup buffers
+=popwin= is used to manage buffers such as ~*Help*~, ~*Completions*~,
+~*compilation*~, and etc. Use =C-g= to close them or most of the time you can
+close them with =q= also. Use ~SPC-r-w~ to view the last closed popup buffer.
+
 *** Ido
 Spacemacs displays the =ido= minibuffer vertically thanks to the
 [[https://github.com/gempesaw/ido-vertical-mode.el][ido-vertical-mode]].

layers/+spacemacs/spacemacs-visual/config.el

@@ -0,0 +1,24 @@
+;;; config.el --- Spacemacs UI Visual Layer Configuration File
+;;
+;; Copyright (c) 2012-2021 Sylvain Benner & Contributors
+;;
+;; Author: Sylvain Benner <sylvain.benner@gmail.com>
+;; URL: https://github.com/syl20bnr/spacemacs
+;;
+;; This file is not part of GNU Emacs.
+;;
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+;;
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+(defvar spacemacs-popwin-last-buffer nil
+  "Last popwin buffer. This is a private variable.")

layers/+spacemacs/spacemacs-visual/funcs.el

@@ -40,6 +40,19 @@
                                  (string-match str (car x))))
                  popwin:special-display-config)))
 
+(defun spacemacs/advice-popwin (orig-fun &rest args)
+  "Advice to `popwin:match-config' around to save the buffer active."
+  (let ((result (apply orig-fun args)))
+    (when result
+      (setq spacemacs-popwin-last-buffer (car args)))
+    result))
+
+(defun spacemacs/last-popwin ()
+  "Resume last popwin buffer."
+  (interactive)
+  (if (buffer-live-p spacemacs-popwin-last-buffer)
+      (select-window (display-buffer spacemacs-popwin-last-buffer))
+    (message "Last popwin buffer not found or killed.")))
 
 ;; zoom
 

layers/+spacemacs/spacemacs-visual/packages.el

@@ -96,6 +96,7 @@
       (popwin-mode 1)
       (spacemacs/set-leader-keys "wpm" 'popwin:messages)
       (spacemacs/set-leader-keys "wpp" 'popwin:close-popup-window)
+      (spacemacs/set-leader-keys "rw" 'spacemacs/last-popwin)
 
       ;; don't use default value but manage it ourselves
       (setq popwin:special-display-config nil)
@@ -114,7 +115,9 @@
       (push '("*grep*"                 :dedicated t :position bottom :stick t :noselect nil            ) popwin:special-display-config)
       (push '("*nosetests*"            :dedicated t :position bottom :stick t :noselect nil            ) popwin:special-display-config)
       (push '("^\*WoMan.+\*$" :regexp t             :position bottom                                   ) popwin:special-display-config)
-      (push '("*Google Translate*"     :dedicated t :position bottom :stick t :noselect t   :height 0.4) popwin:special-display-config))))
+      (push '("*Google Translate*"     :dedicated t :position bottom :stick t :noselect t   :height 0.4) popwin:special-display-config)
+
+      (advice-add 'popwin:match-config :around #'spacemacs/advice-popwin))))
 
 (defun spacemacs-visual/init-zoom-frm ()
   (use-package zoom-frm