I wonder if this blog post would be of any help in understanding the problem. It's three years old, but the basic nature of the rat's nest still persists.
Since you don't have
XSETTINGS never pick up the hinting settings established in the GNOME dialogs. So you'll need to fall back on
fontconfig and setting up your own
$HOME/.fonts.conf, at which point you're writing obtuse XML entries. This Arch Linux Wiki page may help you get started.
EDIT: Have a look at
/usr/share/doc/fontconfig/fontconfig-user.html on your system, which describes the gory details. Happily, you may be able to avoid the goriest of the gory details by using some soft links.
Please be aware that I have not actually tried the following:
Take a look inside
/etc/fonts/conf.avail, which contains a number of pre-made config fragments. Of particular interest will be the files beginning with
11-*, which control how font hinting and sub-pixel positioning is to be done. Some of these are mutually exclusive; for example, you'll only want to pick one of the
First, inside your home directory, create a directory named
cd into it. Next, create soft-links to the config fragments you want to enable, which might look something like:
ln -s /etc/fonts/conf.avail/10-antialias.conf 10-antialias.conf
ln -s /etc/fonts/conf.avail/10-sub-pixel-rgb.conf 10-sub-pixel-rgb.conf
At this point, once you have linked to your preferred fontconfig fragments, it will either magically work the next time you launch a program (I think this will be the case); or you'll need to run
fc-cache to get the system to recognize your changes; or you'll need to log out and back in to your X session (least likely).