[Fontconfig] Disabling automatic font substitution

[Shriramana Sharma]

Hello. I have two requirements re fontconfig:

1) To be able to specify the font used for a particular script like in Firefox.

The "User configuration file" example under
http://www.freedesktop.org/software/fontconfig/fontconfig-user.html
seems to provide mechanism to do per-*language* font selection. I
would like to have per-script font selection. For instance, I want
Lohit Devanagari to be always used for Devanagari whether the language
is Hindi, Marathi, Sanskrit etc. Is this possible?

2) To be able to switch off automatic font substitutions entirely,
either system-wide or per-application.

Due to automatic substitutions, character picker utilities are unable
to indicate whether a font has the glyph for a particular character or
not. Fine, given that their purpose is *character* picking, but still
I'd like to know whether a particular glyph is really coming from a
particular font or not to prevent stylistic inconsistencies when I
create documents using those fonts (but suddenly one glyph is inserted
from another font). It would be good if character pickers are able to
have an option whether to do automatic font substitution or not, but I
guess ultimately it is upto fontconfig to do this or not and the
higher level applications do not have any say in this (correct me if
I'm wrong).

So I'd like to know how to achieve the above two requirements. Thank you.

-- 
Shriramana Sharma ஶ்ரீரமணஶர்மா श्रीरमणशर्मा