KvadrantAppBarButton
fun KvadrantAppBarButton(onClick: () -> Unit, modifier: Modifier = Modifier, enabled: Boolean = true, label: String? = null, content: @Composable BoxScope.() -> Unit)
One circular button: 48×48 px with a 1.5 px ring, and a 26×26 px space in the middle for a glyph. It tilts, like everything else the theme touches.