TextEdit and TrueType Fonts
If your application is using a TrueType font, the default behavior of the Font Manager is to ensure that glyphs fit within the font's ascent and descent. Glyphs that extend beyond the ascent or descent, such as certain
accented fonts, are scaled down to fit. If your application has set the
preserve the original unscaled shape of the glyph, TextEdit sets it to FALSE before it calls DRAWHook to perform any drawing. This is to guarantee that the glyphs whose bounding boxes exceed the font's ascent or descent are scaled
down to prevent them from colliding with other glyphs on the lines above or
below. TextEdit then re stores the preserveGlyph parameter to its previous value before proceeding. See DRAWHook. for details.