dont erase global-mode-string with context label, but add to it

mu4e/mu4e-compose.el

@@ -402,7 +402,8 @@ buffers; lets remap its faces so it uses the ones for mu4e."
 \\{message-mode-map}."
   (progn
     (use-local-map mu4e-compose-mode-map)
-    (set (make-local-variable 'global-mode-string) '(:eval (mu4e-context-label)))
+    (make-local-variable 'global-mode-string)
+    (add-to-list 'global-mode-string '(:eval (mu4e-context-label)))
     (set (make-local-variable 'message-signature) mu4e-compose-signature)
     ;; set this to allow mu4e to work when gnus-agent is unplugged in gnus
     (set (make-local-variable 'message-send-mail-real-function) nil)

mu4e/mu4e-headers.el

@@ -1082,15 +1082,15 @@ the query history stack."
       (setq
 	mu4e~headers-buffer buf
 	mode-name "mu4e-headers"
-	mu4e~headers-last-query expr
-	global-mode-string
-	'(:eval
-	   (concat
-	    (propertize
-	     (mu4e~quote-for-modeline mu4e~headers-last-query)
-	     'face 'mu4e-modeline-face)
-	     " "
-	     (mu4e-context-label)))))
+	mu4e~headers-last-query expr)
+      (add-to-list 'global-mode-string
+                   '(:eval
+                     (concat
+                      (propertize
+                       (mu4e~quote-for-modeline mu4e~headers-last-query)
+                       'face 'mu4e-modeline-face)
+                      " "
+                      (mu4e-context-label)))))
 
     (switch-to-buffer buf)
     (run-hook-with-args 'mu4e-headers-search-hook expr)

mu4e/mu4e-main.el

@@ -75,7 +75,8 @@
     overwrite-mode 'overwrite-mode-binary)
 
   ;; show context in mode-string
-  (set (make-local-variable 'global-mode-string) '(:eval (mu4e-context-label))) 
+  (make-local-variable 'global-mode-string)
+  (add-to-list 'global-mode-string '(:eval (mu4e-context-label)))
   (set (make-local-variable 'revert-buffer-function) #'mu4e~main-view-real))
 
 
@@ -195,7 +196,7 @@ clicked."
   (mu4e~main-view-real nil nil)
   (switch-to-buffer mu4e~main-buffer-name)
   (goto-char (point-min))
-  (setq global-mode-string '(:eval (mu4e-context-label))))
+  (add-to-list 'global-mode-string '(:eval (mu4e-context-label))))
     
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Interactive functions

mu4e/mu4e-view.el

@@ -787,7 +787,8 @@ FUNC should be a function taking two arguments:
   (put 'mu4e~view-attach-map 'permanent-local t)
 
   ;; show context in mode-string
-  (set (make-local-variable 'global-mode-string) '(:eval (mu4e-context-label))) 
+  (make-local-variable 'global-mode-string)
+  (add-to-list 'global-mode-string '(:eval (mu4e-context-label)))
  
   (setq buffer-undo-list t);; don't record undo info