(let's see if that works)
So basically what I'm wondering is if it is possible to run multiple instances of the fontserver (fontconfig?) in parallel for the same desktop session. Then being able to fire up programs connected to either fontserver.
This is Linux so I sorta just assume it is, but better to invoke the Power of Ackshually.
What for, one would ask?
Well, the example use case I'm seeing this for is actually to aid in anti-browser fingerprinting.
As a distro user, one ends up with hundreds of fonts installed. Math, doramas, emojis... Noto by itself adds 80 entries to my LO listing.
Normally that's not an issue, but when in eg.: Firefox, it is. Having enabled browser.use_document_fonts, all those fonts are visible for the browser even with font-visibility measures applied. Have tested it with online benchmarks such as amiunique and browserleaks. What's worse, "use document fonts" is a global setting instead of a site-specific setting, so I can't really fine-tune a session for that -- tho I've already filed Mozilla about that.
But I don't want to uninstall the fonts, I'm using them! I just want for spies to not see them.
So I thought.
Fonts are controlled by a fontserver ("fontconfig").
What if I could have a second fontserver running in my session? One that has a more "normal" set of fonts enabled, such as say the baseline set + language pack fonts for Fedora or Ubuntu, and then Roboto or Noto for good measure. Then I could launch my browser such that it connects to that second fontserver instance...
# example potential code, donut steel
env FONTSERVER_SOCKET=unix:///var/run/fontserver2.sock firefox
And bam! fingerprinters wont be able to see beyond, while I can freely alt-tab to LO and my "handwritten" document.
So yeah. Correct me that this can't be done. Let's do it.