Change "input source text" applet to fixed width

[krakotay]

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Use a monospaced font for the layout indicator to prevent nearby tray items from shifting when the input source changes. This currently only affects two-letter indicators (e.g. us, fr, cn, ru).

[jacobgkau]

Here is an example of the problem this solves:

2026-07-02.14-28-08-cropped.mp4

Here it is on this branch:

2026-07-02.14-28-35-cropped.mp4

I want to mention, using a monospace font is not the only way to solve this. We could just ensure the applet has a fixed width (based on the number of characters, if necessary). We had someone propose using a monospace font for the clock for similar reasons earlier on (particularly for when seconds were enabled), but we were able to fix the shifting without using a monospace font: #635

It's up to UX if the switch to a monospace font is wanted or not. This is ready for QA approval once UX signs off.

[krakotay]

In #635, I saw the comment from this May saying that the fixed-width applet feature still doesn't working on their system, but I havent check it myself.

Also, some input source labels can be longer than two letters. I don't think a fixed-width applet should either truncate a 10-letter input source label or leave empty space for a 2-letter one.

[jacobgkau]

I don't think a fixed-width applet should either truncate a 10-letter input source label or leave empty space for a 2-letter one.

It wouldn't need to. You can just reserve X amount of space per character, can't you? This would only be a problem if a certain font was extremely wide, but the difference usually amounts to pixels.

[krakotay]

Done, it should works.

2026-07-09.09-35-07.mp4

[git-f0x]

but we were able to fix the shifting without using a monospace font

Afaik the issue is still there, but the default Open Sans font has monospace numbers, so it's not noticeable with it.

[krakotay]

@jacobgkau what do you think about?

[maria-komarova]

Using fixed width as @jacobgkau suggested sounds good to me.