PangoGlyphString *glyphs,
PangoliteGlyphString *glyphs,
add_glyph(ThaiFontInfo     *font_info,          PangoGlyphString *glyphs,          gint             cluster_start,          PangoGlyph       glyph,          gboolean         combining){  gint           index = glyphs->num_glyphs;  pango_glyph_string_set_size(glyphs, index + 1);    glyphs->glyphs[index].glyph = glyph;  glyphs->glyphs[index].attr.is_cluster_start = combining ? 0 : 1;    glyphs->log_clusters[index] = cluster_start;}