On Fri, 04 Jul 2025 21:14:52 +0200 Manuel Giraud <manuel@ledu-giraud.fr> wrote:

> Hi,
>
> When viewing diary entry from the calendar, the mode line could be set
> erroneously.  The recipe:
>
>           - Have a file "/tmp/diary" with the following content:
>
> July 4, 2025 A bitter day for many
>
>           - emacs -Q
>           - M-: (setopt diary-file "/tmp/diary") <RET>
>           - M-: (toggle-frame-fullscreen) <RET>
>           - M-: (calendar) <RET>
>           - g d
>           - 2025 <RET>
>           - July <RET>
>           - 4 <RET>
>           - d
>
> Observe that the date in the mode line of the diary view buffer is not
> centered and maybe partly out of sight.  This seems to come from the
> fact that the call to `window-edges' in `calendar-set-mode-line' does
> not return correct values but I can't figure out why.

I think it's because both times `window-edges' is called in
`diary-fancy-display' the selected window is the one displaying the
Calendar, whose `window-width' is the full screen width due to
`toggle-frame-fullscreen', while the window displaying the Fancy Diary
is half as wide.  The following patch seems to fix the problem for me: