Merge commit 'de238b39e335c6814283faa171b35145f124edf2'

1 files changed, 7 insertions, 3 deletions

diff --git a/lisp/simple.el b/lisp/simple.el
index be84e48cf4a..37f92540dde 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -8221,6 +8221,9 @@ CHOICE - the string to insert in the buffer,
 BUFFER - the buffer in which the choice should be inserted,
 BASE-POSITION - where to insert the completion.
 
+Functions should also accept and ignore a potential fourth
+argument, passed for backwards compatibility.
+
 If a function in the list returns non-nil, that function is supposed
 to have inserted the CHOICE in the BUFFER, and possibly exited
 the minibuffer; no further functions will be called.
@@ -8705,7 +8708,7 @@ call `normal-erase-is-backspace-mode' (which see) instead."
                (and (not noninteractive)
                     (or (memq system-type '(ms-dos windows-nt))
 			(memq window-system '(w32 ns))
-                        (and (memq window-system '(x))
+                        (and (eq window-system 'x)
                              (fboundp 'x-backspace-delete-keys-p)
                              (x-backspace-delete-keys-p))
                         ;; If the terminal Emacs is running on has erase char
@@ -8716,6 +8719,8 @@ call `normal-erase-is-backspace-mode' (which see) instead."
              normal-erase-is-backspace)
            1 0)))))
 
+(declare-function display-symbol-keys-p "frame" (&optional display))
+
 (define-minor-mode normal-erase-is-backspace-mode
   "Toggle the Erase and Delete mode of the Backspace and Delete keys.
 
@@ -8751,8 +8756,7 @@ See also `normal-erase-is-backspace'."
   (let ((enabled (eq 1 (terminal-parameter
                         nil 'normal-erase-is-backspace))))
 
-    (cond ((or (memq window-system '(x w32 ns pc))
-	       (memq system-type '(ms-dos windows-nt)))
+    (cond ((display-symbol-keys-p)
 	   (let ((bindings
 		  '(([M-delete] [M-backspace])
 		    ([C-M-delete] [C-M-backspace])