>
>
>------ Original Message ------
> 土曜日, 2025/5/3  17:37, Arash Esbati<arash@gnu.org> によって書かれました:
>
>Hi Keita,
>
>Ikumi Keita <ikumi@ikumi.que.jp> writes:
>
>> I think we should use `derived-mode-p' here instead of comparing
>> `major-mode' directly.
>
>Thanks for your response.  Something like this?
>
>--8<---------------cut here---------------start------------->8---
>diff --git a/tex.el b/tex.el
>index 3d28b2c6..0d47988c 100644
>--- a/tex.el
>+++ b/tex.el
>@@ -6188,10 +6188,13 @@ See `TeX-electric-math'."
>              (re-search-forward "\\=\\$\\$\\([^z-a]*\\)\\$\\$" (mark) t)))
>     (replace-match "\\1" t)
>     (set-mark (match-beginning 0)))
>-   ;; $...$ to $$...$$
>+   ;; $...$ to $$...$$ or \[...\] dep. on mode:
>    ((and (eq last-command #'TeX-insert-dollar)
>          (re-search-forward "\\=\\$\\([^z-a]*\\)\\$" (mark) t))
>-    (replace-match "$$\\1$$" t)
>+    (replace-match (if (derived-mode-p '(LaTeX-mode docTeX-mode))

Well, since docTeX-mode is already derived from 
LaTeX-mode, we can just do
(derived-mode-p 'LaTeX-mode)
:-)

>+                       "\\\\[\\1\\\\]"
>+                     "$$\\1$$")
>+                   t)
>     (set-mark (match-beginning 0)))
>    ;; \(...\) to \[...\]
>    ((and (eq last-command #'TeX-insert-dollar)
>--8<---------------cut here---------------end--------------->8---
>
>Best, Arash
>