system-wide location for dictionary files and dictionary file name format

[Erik Quaeghebeur]

> Firefox has no problem using ar.{aff,dic} for Arabic, neither does
> gtkspell (or whatever GTK+ apps use).

I can confirm. Firefox also deals nicely with the four French variants,
even listing “French (Moderne)” for fr-moderne (doesn't do that for the
others though, just gives “fr-reforme1990”, don't know why, perhaps the
8-character limit in bcp47… must check). KDE (KTextEditor) also does
things nicely,  giving “français (France) [reforme1990]” (of course here
the “(France)” shouldn't be there, but that's minor).

What are the experiences of others, with other software (emacs, vim,…)?