Converts from an index within a #PangoLayout to the onscreen position
corresponding to the grapheme at that index, which is represented
as rectangle. Note that <literal>pos->x</literal> is always the leading
edge of the grapheme and <literal>pos->x + pos->width</literal> the trailing
edge of the grapheme. If the directionality of the grapheme is right-to-left,
then <literal>pos->width</literal> will be negative.
Converts from an index within a #PangoLayout to the onscreen position corresponding to the grapheme at that index, which is represented as rectangle. Note that <literal>pos->x</literal> is always the leading edge of the grapheme and <literal>pos->x + pos->width</literal> the trailing edge of the grapheme. If the directionality of the grapheme is right-to-left, then <literal>pos->width</literal> will be negative.