highContrast property
Whether the platform's increase-contrast switch is on.
Under it every rung draws its outline as an opaque line of the colour that stands out most against the level under it (GlassFinish.highContrastRim), kHighContrastRimWidthLogical wide, instead of the calibrated additive white. That is what Apple's switch does to its own glass — the translucency stays, the edge becomes visible — and the calibrated rim cannot be made to do it by turning it up, because it adds and a light level swallows an addition.
Nothing else changes: not the rung, not the tint, not the label. A user who wants the translucency gone has the other switch, and it goes to GlassTier.opaque.
Implementation
final bool highContrast;