GtkFontChooser: enable access to installed font documentation & help
( This is a feature request meant to correspond to the documentation portion of gnome-font-viewer#5 )
Many distribution-provided font packages install auxiliary files (e.g., documentation, help, licenses/EULAs, specimens, screenshots, JS/CSS examples, etc) under /usr/share/doc/packagename/ or /usr/share/doc/fontfamily/, etc. Sometimes this information is intended to be helpful to the user when working with the font in a document, such as how to access language-specific OpenType features, what the variation axes do, or simply what the historical model or intent of the design is.
Those auxiliary documents are not made accessible to the user in any current applications. GtkFontChooser could improve usability by providing links to such files when exploring/experimenting with font selection. Implementing this sort of linkage in the GTK+ component would make it available to a wide range of applications.
Note that it is also possible for per-user, local fonts to have similar documentation. The gnome-font-viewer issue linked to above suggests installing that material in a well-known location like ~/.local/share/doc/, but currently it is not installed anywhere (at least by system utilities).
Determining the correct subdirectory under /usr/share/doc/ for a given font is not automatic and could prove to be tricky. Standardizing the structure and nomenclature of all font packages across all distributions might do the trick, but that certainly ain't likely anytime soon....
Possibly caching that information in a local metadata db would be better. I'm sure others will have other, probably better, ideas.