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Noto Sans Mono: missing monospaced flag - not selectable in some applications (TTF only) #540
Description
'Noto Sans Mono' implies being a monospaced font and it works great for programming and on the console appearing monospaced. Yet, apparenlty some characters must have divergent width because it is missing the monospaced flag.
This causes some applications listing only monospaced fonts (e.g. mobaxterm) to not list the font, or e.g. Putty requiring to set 'Allow selection of variable-pitch fonts' to be able to select it.
A version of this font actually being monospaced or just having the flag set would be a great quality of life improvement.
for the documentation it would be great to know which characters violate the monospaced criterium?
tested with latest 2.014 on windows
Activity
lkintact commentedon Sep 10, 2025
I stumbled on that very issue - gVim on MS-Windows doesn't see TrueType "Noto Sans Mono" fonts (
NotoSansMono-*.ttffiles linked on https://notofonts.github.io/).It does however see OpenType variants of the font (
NotoSansMono-*.otffiles on the same page).volkb79 commentedon Sep 11, 2025
i tested the otf on windows, i can confirm this. so the issue is with the ttf only .
[-]Noto Sans Mono: missing monospaced flag - not selectable in some applications[/-][+]Noto Sans Mono: missing monospaced flag - not selectable in some applications (TTF only)[/+]t4rik commentedon Oct 11, 2025
In Fedora 42 and 43, Terminal can't detect Noto Sans Mono.
From Font Manager show Noto Sans Mono --> Proportional
es20490446e commentedon Oct 11, 2025
See #234.
micw commentedon Dec 19, 2025
Another negative effect: "Noto Sans Mono" is the preferred monospace font in my system. That is not working. So it's falling back to "Noto Sans" and e.g. Firefox is showing all "monospace" texts in Noto Sans...
es20490446e commentedon Dec 19, 2025
Upstream bug: shall be closed here.
Follow here.
simoncozens commentedon Dec 20, 2025
The problem we have here is that Noto Sans Mono is mostly monospaced. There are a number of double-width ligatures. So everything we claim about it turns out to be a lie. The font compiler, which is responsible for the monospace bit settings, is doing the right thing - it is not monospaced, so we don't claim that it is. But of course this causes the problems we see in this issue. If we were able to trick the font compiler into setting the monospaced bits, or if we were to set them manually, then we fail into the problems we see in #234.
The solution is probably to get rid of the non-monospaced ligatures.
micw commentedon Dec 20, 2025
Or not to claim Noto Sans Mono being a mono font.
simoncozens commentedon Dec 20, 2025
We don't claim it; the monospaced flag is unset.
Are you saying that some software is looking at the font name and making inferences about the name instead of the flags in the font? That's a bug.
micw commentedon Dec 20, 2025
Very good point. I'm coming from the view of an end user (never dealed with any font settings). On my system (ArchLinux) Noto Sans Mono seems to be everywhere as the de-facto default monospace font. I stumbled across this when I created a theme for my blog and got monospaced text not working on firefox.
Took me more than an hour to find the root cause. Whatever I did, the system ended up in using "Noto Sans" as the final fallback. Until I uninstalled the noto package (along with it's fontconfig rules). But then I had to set the new monospace font on several places.
Artoria2e5 commentedon Dec 20, 2025
Fontconfig does not purely rely on the flag because it's nonexistent for some formats (and those that exist have different semantics when it comes to grid vs true-mono). Fc actually examines the advance widths of all the glyphs to figure out whether they are all 1x or 2x of a fixed advance width. (This has persisted after the Rust rewrite, so the fc side is still https://gitlab.freedesktop.org/fontconfig/fontconfig/-/issues/176.)
Downstream applications should use FC_DUAL when possible. There is already a Qt bug for that. There potentially needs to be a bug for Gnome font manager or the broader Gtk3 but I'm too lazy to check the source now.
es20490446e commentedon Dec 21, 2025
"Mono" means "monospaced" 😌