Fullscreen video gesture overlay

A fullscreen video screen is three siblings in one box, in this order:

// adapted
Box {
    VideoSurface(Modifier.fillMaxSize(), isInPipMode = isInPipMode)   // always on
    if (!isInPipMode) {
        Row(Modifier.fillMaxSize()) {          // gesture layer: two seek zones
            SeekZone(Modifier.weight(1f), onSeek = { seekBack() })
            SeekZone(Modifier.weight(1f), onSeek = { seekForward() })
        }
        Crossfade(chromeVisible) { if (it) Chrome(...) }               // chrome, on top
    }
}