diff --git a/examples/validation/discussion/440.py b/examples/validation/discussion/440.py
new file mode 100644
index 00000000..ee8b90dc
--- /dev/null
+++ b/examples/validation/discussion/440.py
@@ -0,0 +1,51 @@
+import asyncio
+from trame.app import get_server
+from trame.ui.html import DivLayout
+from trame.widgets import trame
+from trame.decorators import TrameApp, controller
+
+
+def toggle_node(node, node_id):
+    if node.get("id") == node_id:
+        new_visible = (node.get("visible") + 1) % 2
+        return {**node, "visible": new_visible}
+    return node
+
+
+@TrameApp()
+class App:
+    def __init__(self, server=None):
+        self.server = get_server(server, client_type="vue3")
+        self.ui = self._build_ui()
+
+    @property
+    def state(self):
+        return self.server.state
+
+    def toggle_visibility(self, node_id):
+        with self.state:
+            self.state.pipeline = [toggle_node(n, node_id) for n in self.state.pipeline]
+
+    @controller.add_task("on_server_ready")
+    async def auto_toggle(self, **kwargs):
+        while True:
+            for node_id in ["1", "2"]:
+                await asyncio.sleep(0.1)
+                self.toggle_visibility(node_id)
+
+    def _build_ui(self):
+        with DivLayout(self.server) as layout:
+            trame.GitTree(
+                sources=(
+                    "pipeline",
+                    [
+                        {"id": "1", "parent": "0", "visible": 1, "name": "Mesh"},
+                        {"id": "2", "parent": "1", "visible": 1, "name": "Contour"},
+                    ],
+                ),
+            )
+
+
+if __name__ == "__main__":
+    app = App()
+    app.server.start()