Test

gistfile1.txt

// Main video widget.
class VideoState extends State {
  Widget build(...) {
    return Row(
      childred: [
        SideBar(), // can be hidden (depending on this overlay which can be created deeper should change its sze as VideoMonitor widget will also be resized.
        VideoMonitor(), // contains VideoMonitorGrid
      ],
    );
  }
}

// VideoMonitor which is part of Video widget.
class VideoMonitorState extends State {
  final layerLink = LayerLink();
  Widget build(...) {    
    Expaned(
      child: CompositedTransformTarget(
      link: layerLink,
      child: Provider.value(
        value: layerLink,
        child: SomeOtherWidgets(
          child: VideoMonitorGrid(), 
        )
      ),    
    ),
  ),
}

// Wrapper for different grid layouts
class VideoMonitorGridState extends State {
  Widget build(...) {
    return SomeOtherWidgets(
      return specificDesignGridBuilder(this); // depending of selector specific designed widget is built.
    );
  }
}

// Specific video layout
class VideoMonitor2x2 extends State {
  Widget build(...) {
    // Widget chich will be zoomed
    return VideoCameraZoomed(
      child: GestureDetector(
        onDoubleTap: _showOverlay(),
        child: widget.child,
      ),
    );
  }
  
  void _showOverLay() {
    final layerLink = context.read<LayerLink>();
    final cellRect = context.getRect();
    final gridRect = Rect.fromLTWH(
      layerLink.leader.offset.dx,
      layerLink.leader.offset.dx,
      layerLink.leaderSize.width,
      layerLink.leaderSize.height,      
    );
    final rectAnimation = RectTween(begin: cellRect, end: gridRect).animate(controller);
    _overlayEntry = OverlayEntry(
      builder: (_) {
        return CompositedTransformFollower(
          link: layerLink,
          showWhenUnlinked: false,
          offset: -gridRect.topLeft,
          child: GestureDetector(
            onDoubleTap: _hideOverlay(),
            child: AnimatedBuilder(
              builder: (contet,child) {
                return Stack(
                  children: [
                    Positioned(
                     // left,top,width, rect from rectAnimation
                     child: widget.child // zooming widget is hare
                    ),
                  ],
                );
              }
            ),
          ),          
        );
      }
    );
  }
}

So when I change width of Sidebar, VideoMonitor's width is also changed. Along the chain created Overlay 
expanded (only first time). If I show Sidebar again, i.e. width of the VideoMonitor() become less, than Overlay's width must
also decreased but it does not so because `gridRect` is not changed. I need some how to force update the OverlayEntry's builder.