rework & refactor spw/set-tmux-background-mode

1 files changed, 18 insertions, 9 deletions

diff --git a/.emacs.d/init.el b/.emacs.d/init.el
index 0ba5c8c0..8c864913 100644
--- a/.emacs.d/init.el
+++ b/.emacs.d/init.el
@@ -116,15 +116,24 @@ windows side-by-side in the frame."
 			      :height (if scale-up-p 151 120)))))))
 (add-to-list 'window-size-change-functions #'spw/maybe-scale-basic-faces)
 
-;; `frame--current-backround-mode' assumes that TERM=screen-256color means a
-;; dark background.  But if we're in tmux then I can always have dark-on-light
-;; by typing C-\ W (see ~/.tmux.conf).
-(defun spw/set-tmux-background-mode (frame)
-  (when (cl-find-if (apply-partially #'string-prefix-p "TMUX=")
-		    (frame-parameter frame 'environment))
-    (let ((frame-background-mode 'light))
-      (frame-set-background-mode frame))))
-(add-to-list 'after-make-frame-functions #'spw/set-tmux-background-mode)
+;;; `frame--current-backround-mode' assumes that TERM=screen-256color means a
+;;; dark background.  But if we're in tmux then I can always have a light
+;;; background by typing C-\ W (see ~/.tmux.conf).
+
+;; Handle 'emacs -nw' initial frames.
+(when (and (framep terminal-frame)
+	   (cl-find-if
+	    (apply-partially #'string-prefix-p "TMUX=") initial-environment))
+  (set-terminal-parameter terminal-frame 'background-mode 'light))
+
+;; Handle 'emacsclient -tc' frames.
+;; Require that TMUX is set in the frame's own environment parameter.
+;; The hook is run with the new tty frame selected.
+(defun spw/set-tmux-background-mode ()
+  (when (and (frame-parameter nil 'environment)	; check it has one
+	     (getenv "TMUX" (selected-frame)))
+    (set-terminal-parameter nil 'background-mode 'light)))
+(add-hook 'tty-setup-hook #'spw/set-tmux-background-mode)
 
 (custom-set-variables
  ;; custom-set-variables was added by Custom.