horizontalInset property
Inset from each screen edge to the pinned chrome, in logical pixels.
Defaults to GlassNavPinnedMetrics.horizontalPadding, which is what GlassAppBar insets its own chrome by — so a bar the package draws at both ends already agrees with itself and passes nothing.
A bar the app draws is the case for it. The chrome hoists and hands back on its own schedule — a presented sheet gives it to the route, a transition takes it away again — and each hand-over is invisible only while the two renderings land on the same guide. A bar aligned to its app's page gutter rather than to this default passes that gutter here.
Implementation
final double? horizontalInset;