bug#50752: 28.0.50; easy-menu-define lowers the menu-bar key

[Shuguang Sun]

Hi,

I'm using the package pdf-tools to view PDF files. However the popu-menu does't work in recent emacs snapshot. I find it is due the automaticly lowering the menu-bar by easy-menu-deine. Is it a feature or bug?

Of pdf-tools (from melpa or from http://github.com/vedang/pdf-tools/), in the pdf-misc.el it defines

```

(easy-menu-define nil pdf-misc-menu-bar-minor-mode-map
  "Menu for PDF Tools."
  `("PDF Tools"
    ["Go Backward" pdf-history-backward
     :visible (bound-and-true-p pdf-history-minor-mode)
     :active (and (bound-and-true-p pdf-history-minor-mode)
                  (not (pdf-history-end-of-history-p)))]
```

And the responding function

```

(defun pdf-misc-popup-context-menu (event)
  "Popup a context menu at position determined by EVENT."
  (interactive "@e")
  (popup-menu
   (cons 'keymap
         (cddr (lookup-key pdf-misc-menu-bar-minor-mode-map
                           [menu-bar PDF\ Tools])))))
```

However, it can't find the key of "PDF\ Tools". Instead, I find in the `pdf-misc-menu-bar-minor-mode-map`, that,

```

(keymap
 (menu-bar keymap
           (pdf\ tools menu-item #1="PDF Tools"
                       (keymap #1#
                               (Go\ Backward menu-item "Go Backward" pdf-history-backward :enable
```

It becomes lower case (`pdf\ tools`).

If I change the case, the function works again:

```(defun pdf-misc-popup-context-menu (event)
  "Popup a context menu at position determined by EVENT."
  (interactive "@e")
  (popup-menu
   (cons 'keymap
         (cddr (lookup-key pdf-misc-menu-bar-minor-mode-map
                           [menu-bar pdf\ tools])))))
```

Best Regards,

Shuguang Sun

In GNU Emacs 28.0.50 (build 1, x86_64-w64-mingw32)
 of 2021-09-21 built on YJ190169-SSG
Repository revision: 5b962a7ad8d0acfe40a41ce139059b9c8e46f666
Repository branch: master
Windowing system distributor 'Microsoft Corp.', version 10.0.19043
System Description: Microsoft Windows 10 Pro (v10.0.2009.19043.1237)

Configured using:
 'configure --without-pop --with-native-image-api
 --with-native-compilation --without-compress-install
 '--program-transform-name=s/^ctags$/ctags.emacs/''

Configured features:
ACL DBUS GIF GMP GNUTLS HARFBUZZ JPEG JSON LCMS2 LIBXML2 MODULES
NATIVE_COMP NOTIFY W32NOTIFY PDUMPER PNG RSVG SOUND THREADS TIFF
TOOLKIT_SCROLL_BARS XPM ZLIB