GlassBarItem.spacer constructor
const
GlassBarItem.spacer()
Splits the shared glass background, mirroring SwiftUI's
ToolbarSpacer(.fixed) and UIKit's UIBarButtonItem.fixedSpace.
Items on either side of a spacer render in separate glass capsules, the
standard gap apart. Across a route transition each capsule follows its
items, matched by id where they have one, and a capsule that only one
route has buds out of the one beside it, or merges back into it.
Implementation
const factory GlassBarItem.spacer() = GlassBarSpacer;