Up to now, we simply took a snapshot of the Graphics State after the
`prep' table has been executed, and right before a glyph's bytecode
was run it got reloaded. However, as Greg Hitchcock has told us in
private communication, reference points get reset to zero in the MS
rasterizer and we follow in due course. While reasonable, this is
undocumented behaviour.
Most notably, this fixes the rendering of Arial's `x' glyph in
subpixel hinting mode.
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