void pango_layout_index_to_pos ( PangoLayout* layout, int index_, PangoRectangle* pos )
Converts from an index within a
PangoLayout to the onscreen position
corresponding to the grapheme at that index.
The returns is represented as rectangle. Note that
always the leading edge of the grapheme and
pos->x + pos->width the
trailing edge of the grapheme. If the directionality of the grapheme
is right-to-left, then
pos->width will be negative.
Byte index within
Rectangle in which to store the position of the grapheme.
The argument will be set by the function. The data is owned by the instance.