bug#46476: Feature request: Right-aligning part of the modeline

[Paweł Kraśnicki]

> If people use :align-to, then what would be the advantage of providing
> %-constructs to produce the same?

Well, the only advantage is that people wouldn't need to install an external
package or write a short but advanced piece of Lisp. I think that right
alignment is such a commonly used feature that it would be good to have it
accessible very easily. (Center alignment and segments are less popular.)
I actually got the idea for using %= in particular from Vim, which has right
alignment under this %-construct.

> That'd require two passes to generate the mode-line display, right?

I think so. Emacs would have to first expand the modeline constructs in the
segments separately into some internal data structure, then decide which ones to
actually display.