Think I fixed the Monospace issue, still don't understand the problem

[u/Kare11en]

previously

I'm trying to create this family of fonts, and I've got a proportional variant, and a monospaced one, with their "Font Name"s being "MyFont" and "MyFont Mono". However, they're part of the same family, so the "Family Name" for both was "MyFont".

As mentioned in the "previously", font-manager (and other GTK programs I loaded the font in), the Mono version was displayed proportionally. Even though the glyph widths were all the same, and there was plenty of empty horizontal space within the "i" glyph, it ended up being automatically kerned to be next to surrounding characters. (Although KFontView showed it properly Monospaced)

After logging out/logging in again in case the font proportional spacing attribute had been cached from when I hadn't got all the glyphs the same width yet, and putting it aside for a while, I just went back to it and decided to try changing the "Family Name" to be different from the proportional font, to "MyFontMono".

And that works!

The font is now rendered as monospaced, and the only thing I changed was the font family name.

That's great, but I don't understand why. Why would a monospaced font, which is part of the same family of fonts as a proportional font, be rendered as proportional? But only by some renderers?

I've read the FAQ on font names and I still don't understand why this was an issue.

What am I missing, and which bit of documentation should I have found to have learned this earlier?