Variable width faces support

[Vincent-P]

Is your feature request related to a problem? Please describe.
I really enjoy having variable-width fonts for every UI fonts, but I can't do this with doom-modeline.
If for example I set doom-modeline-buffer-path or doom-modeline-buffer-file face family to "Noto Sans" with this: (set-face-attribute 'doom-modeline-buffer-path nil :family "Noto Sans"), the buffer in inactives modelines will still be displayed using a fixed-width font.

Describe the solution you'd like
Is it possible to have inactive variant for each face? Maybe there is an even better solution?

Describe alternatives you've considered
Well there isn't any alternative so I am stuck with fixed-width font for now...

Additional context

[seagle0128]

You may need to change the faces of mode-line and mode-line-inactive, but the icons may be not displayed corrected.

[Vincent-P]

Yes it breaks the icon font that's why I didnt mention it.

[Vincent-P]

I am going to try thanks!

[seagle0128]

I committed a patch to support different fonts in mode line. Just need to set mode-line and mode-line-inactive face. All icons should be Okay now. The right position of the segment may not be accurate but I think it's a minor issue.

[Vincent-P]

Now I have this issue: #300, not necessarily in org mode.

[seagle0128]

Are you using doom?

[Vincent-P]

No.
I added this to my config:

  (set-face-attribute 'mode-line nil :family "Noto Sans")
  (set-face-attribute 'mode-line-inactive nil :family "Noto Sans")

The mode indicator in the inactive mode-line is a weird character instead of an icon, it also happens with other fonts.

[seagle0128]

A new face doom-modeline-icon-inactive is introduced. Hope all icons can be displayed correctly now.

[Vincent-P]

It's perfect now thanks a lot! :)

[seagle0128]

@Vincent-P Great! Can you please help to test with the default font as well?