<parameter>sets</parameter>, creates patterns from those
fonts containing only the objects in <parameter>object_set</parameter> and returns
the set of unique such patterns.
+If <parameter>config</parameter> is NULL, the default configuration is checked
+to be up to date, and used.
@@
@RET@ FcPattern *
<function>FcConfigSubstitute</function> and
<function>FcDefaultSubstitute</function> have been called for
<parameter>pattern</parameter>; otherwise the results will not be correct.
+If <parameter>config</parameter> is NULL, the current configuration is used.
Returns NULL if an error occurs during this process.
@@