update example project

example/lib/camera_menu.dart

@@ -0,0 +1,58 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/widgets.dart';
+import 'package:flutter_filament/filament_controller.dart';
+
+class CameraMenu extends StatefulWidget {
+  final FilamentController? controller;
+
+  CameraMenu({super.key, required this.controller});
+
+  @override
+  State<StatefulWidget> createState() {
+    return _CameraMenuState();
+  }
+}
+
+class _CameraMenuState extends State<CameraMenu> {
+  bool _frustumCulling = true;
+
+  final FocusNode _buttonFocusNode = FocusNode(debugLabel: 'Camera Menu');
+
+  @override
+  void didUpdateWidget(CameraMenu oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    if (widget.controller != oldWidget.controller) {
+      setState(() {});
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return MenuAnchor(
+      childFocusNode: _buttonFocusNode,
+      menuChildren: <Widget>[
+        MenuItemButton(
+          child: Text("Camera"),
+          onPressed: () {},
+        ),
+      ],
+      builder:
+          (BuildContext context, MenuController controller, Widget? child) {
+        return Align(
+            alignment: Alignment.bottomLeft,
+            child: TextButton(
+              onPressed: widget.controller?.hasViewer != true
+                  ? null
+                  : () {
+                      if (controller.isOpen) {
+                        controller.close();
+                      } else {
+                        controller.open();
+                      }
+                    },
+              child: const Text("Camera"),
+            ));
+      },
+    );
+  }
+}