tint

The tint painted over the blur, chosen to keep the status bar's icons legible: translucent white under dark icons, translucent black under light ones.

The icons' colour is read from the window — the isAppearanceLightStatusBars flag the host set with enableEdgeToEdge or WindowInsetsController — rather than from the system's night mode, because the two disagree in exactly the hosts this scrim is for. A viewer themed from its PdfActivityConfiguration tints its icons for the configuration's ThemeMode, so a light document on a dark-mode device has dark icons, and a scrim keyed on the system would darken the strip under them. When no window can be reached (a preview, a detached composition) it falls back to isSystemInDarkTheme.

Both tints are opaque enough to carry the strip alone on devices without blur support (below API 31), and both disappear into a page that already matches them, so the scrim is only ever seen where it is doing something.

The flag is re-read when the composition is recreated (a configuration change, a theme swap through LocalNutrientThemeKey), which is when hosts set it. It is not observed live: a host that flips it at runtime without a recomposition keeps the previous tint until one happens.