The PANGO_GLYPH_INVALID_INPUT macro represents a PangoGlyph value that has a special meaning of invalid input. gtk.Layout produces one such glyph per invalid input UTF-8 byte and such a glyph is rendered as a crossed box.

Note that this value is defined such that it has the PANGO_GLYPH_UNKNOWN_FLAG on.

enum GLYPH_INVALID_INPUT = 4294967295;