Re: Operation of format-mode-line

[Eli Zaretskii]

> Date: Wed, 24 Jul 2024 13:08:15 +0000
> From: Heime <heimeborgia@protonmail.com>
> Cc: help-gnu-emacs@gnu.org
> 
> > I meant you don't need to do anything except change the number,
> > i.e. replace "12" with "20" (or whatever number you want there).
> 
> How can I do it with elisp code ?   I am constructing my own modeline.

mode-line-format is a variable, so you can use setq to modify its
value.  Or you could modify just the value of
mode-line-buffer-identification, another variable (which is used to
construct the value of mode-line-format), which is where "%12b" comes
from.

More generally, take a look at lisp/bindings.el, where all the parts
of mode-line-format are defined and then used to produce the final
value of that variable.