handleBorrowed glyph; reacquire after font or atlas changes.
Writable live glyph properties, including the three numeric bitfields.
Colored, Visible and Codepoint use native getters/setters retaining the handle; metrics and UVs keep their shared-buffer fast path. Flag setters accept only numeric 0 or 1; Codepoint accepts integers in [0, 0x3fffffff]. Non-numbers throw TypeError; non-finite, fractional or out-of-range numbers throw RangeError without modifying the glyph. The glyph remains borrowed: retaining this view does not keep its font or atlas alive.
Access glyph geometry and texture coordinates in native storage.