How to notify pango with a change of FcConfig?

[Kang Jeong-Hee <Keizi mail co kr>]

FcConfig provide APIs to add a file or dir at runtime;
  FcConfigAppFontAddFile() and FcConfigAppFontAddDir().

How to make pango know the change of FcConfig?
Or, Does it happen automatically when FcConfig changed
to reload it into pango?

$ grep FcConfig ~/cvs/pango/pango/* -I
pangoft2-fontmap.c:  FcConfigSubstitute (NULL, pattern, FcMatchPattern);
pangoxft-fontmap.c:  FcConfigSubstitute (NULL, pattern, FcMatchPattern);

is all that I've found, thus, I don't know how to do what I want.

Thanks in advance.
Kang Jeong-Hee.