GlassThemeSettings class

A partial override of LiquidGlassSettings for use in GlassThemeVariant.

Unlike LiquidGlassSettings, every field here is optional (null). A null value means "do not override — use the widget's own default".

This solves the footgun where setting a single property like thickness in the theme would silently zero out all other settings (e.g. glassColor would revert to fully transparent because the constructor default is Color.fromARGB(0, …)).

Usage

GlassTheme(
  data: GlassThemeData(
    light: GlassThemeVariant(
      // Only thickness and blur are overridden — glassColor, refractiveIndex,
      // lightIntensity, etc. continue to use each widget's own defaults.
      settings: GlassThemeSettings(
        thickness: 40,
        blur: 6,
      ),
    ),
  ),
  child: …,
)

Merge order

1. Widget's own explicit settings parameter (highest priority)
2. Theme GlassThemeSettings — only non-null fields applied
3. Widget's built-in per-widget defaults (lowest priority)