pub fn size_class() -> Option<SizeClass>Expand description
The current window’s size class, or None on a backend that does not report one yet.
Tracked: a piece that lays out from this rebuilds when the window crosses a breakpoint.
Outside a window’s content build this reads the primary window, so a long-lived effect that
wants a secondary window’s class must capture its root at build time and use
window_size_class, the same discipline toolbar_reactive follows.