bug#47092: Icecat sandbox causes issues with fonts in --pure env

[Martin]

Hello,
whenever I'm trying to run 'guix environment --pure --ad-hoc icecat -- 
icecat' or similar commands in a --container I'm ending up with some 
tofu ugly font fallback box glyphs in the app. However everything works 
fine running 'guix environment --ad-hoc icecat -- icecat'. Moreover I've 
noticed that when I edit the default value of 
"security.sandbox.content.level" from 4 to 2 in "about:config" then the 
problem disappear and the fonts are properly displayed in --pure and 
--container env. I was trying to install all possible fonts, running 
'fc-cache -rfv' and analyze the icecat logs with "MOZ_SANDBOX_LOGGING=1" 
to include blocking paths into the 
"security.sandbox.content.read_path_whitelist" but still I couldn't fix 
this issue with the icecat default sandbox level. Any ideas how to solve 
it in Guix System and what are the side effects of using 
"security.sandbox.content.level=2" in --pure env?

Kind regards!
Martin

security.sandbox.content.read_path_whitelist