Inkscape 0.92.0 (snap) fonts problem - Ubuntu 16.10
this is a known issue with the snap package format for Ubuntu. As far as I understand, they do only find fonts that you put into the .fonts directory in your home directory.
https://bugs.launchpad.net/inkscape/+bug/1655609
Check which Inkscape you use: snap or apt.
In the Ubuntu 18.04 AppCenter, there are two different versions of Inkscape, one from the Snap Store, one from ubuntu-bionic-universe.
If you have the first one, you’re in trouble, there are no fonts you have installed and a Windows XP-like interface. Remove this version and get the second one and you'll be happy then.
I just went through this with Ubuntu 18.04 and Inkscape 0.92. Putting fonts (TrueType) in ~/fonts
did not work. Moving them to /usr/share/fonts/truetype
did.
After putting the fonts in ~/fonts
and not seeing them in Inkscape found here interfaces: mount host system fonts in desktop interface #3889 I executed
$ snap refresh --channel=edge core
... which didn't help.
I then move the fonts to /user/share/fonts/truetype
and could finally see the fonts in Inkscape.