A #PangoGlyphItem is a pair of a #PangoItem and the glyphs
resulting from shaping the text corresponding to an item.
As an example of the usage of #PangoGlyphItem, the results
of shaping text with #PangoLayout is a list of #PangoLayoutLine,
each of which contains a list of #PangoGlyphItem.
PangoGlyphItem:
A #PangoGlyphItem is a pair of a #PangoItem and the glyphs resulting from shaping the text corresponding to an item. As an example of the usage of #PangoGlyphItem, the results of shaping text with #PangoLayout is a list of #PangoLayoutLine, each of which contains a list of #PangoGlyphItem.