emacs global-set-key M-似乎被覆盖，并且在升级emacs中的某些软件包后不起作用

Question

这是我的.emacs内容。有人可以帮忙。

(global-set-key (kbd "M-,") 'pop-tag-mark)
(setq projecthome "/tmp/myproject")
(add-hook 'ess-mode-hook
          (lambda ()
            (let ((ess-build-tags-command "rtags('%s', recursive = TRUE, pattern = '\\\\.[RrSs](rw)?$',ofile = '%s')")
                  (my-tags-file (concat projecthome "/R/TAGS")))
              (ess-build-tags-for-directory (concat projecthome "/R/") (concat projecthome "/R/TAGS"))
              (sleep-for 5)
              (visit-tags-table my-tags-file)
          )))