diff --git a/plugins/kernel/pyproject.toml b/plugins/kernel/pyproject.toml
index 1dd9f67..2650631 100644
--- a/plugins/kernel/pyproject.toml
+++ b/plugins/kernel/pyproject.toml
@@ -23,6 +23,7 @@ classifiers = [
 ]
 dependencies = [
   "txl",
+  "asphalt",
   "python-dateutil >=2.8.2",
   "pycrdt >=0.8.11,<0.9.0",
 ]
diff --git a/plugins/kernel/txl_kernel/driver.py b/plugins/kernel/txl_kernel/driver.py
index c25babf..840d9ef 100644
--- a/plugins/kernel/txl_kernel/driver.py
+++ b/plugins/kernel/txl_kernel/driver.py
@@ -2,6 +2,7 @@
 import time
 from typing import Dict
 
+from asphalt.core import Event, Signal
 from pycrdt import Array, Map
 
 from .message import create_message
@@ -31,7 +32,15 @@ def send(self, buffers):
         asyncio.create_task(self.send_message(msg, self.shell_channel, change_date_to_str=True))
 
 
+class BusyEvent(Event):
+    def __init__(self, source, topic, busy: bool):
+        super().__init__(source, topic)
+        self.busy = busy
+
+
 class KernelMixin:
+    busy = Signal(BusyEvent)
+
     def __init__(self):
         self.msg_cnt = 0
         self.execute_requests: Dict[str, Dict[str, asyncio.Queue]] = {}
@@ -89,6 +98,12 @@ async def recv(self):
             elif msg_type == "comm_msg":
                 for comm_handler in self.comm_handlers:
                     comm_handler.comm_msg(msg)
+            elif msg_type == "status":
+                execution_state = msg["content"]["execution_state"]
+                if execution_state == "idle":
+                    self.busy.dispatch(False)
+                elif execution_state == "busy":
+                    self.busy.dispatch(True)
             msg_id = msg["parent_header"].get("msg_id")
             if msg_id in self.execute_requests:
                 # msg["header"] = str_to_date(msg["header"])
diff --git a/plugins/notebook_editor/txl_notebook_editor/components.py b/plugins/notebook_editor/txl_notebook_editor/components.py
index 73f3bd7..ef71195 100644
--- a/plugins/notebook_editor/txl_notebook_editor/components.py
+++ b/plugins/notebook_editor/txl_notebook_editor/components.py
@@ -7,9 +7,12 @@
 import anyio
 from asphalt.core import Component, Context
 from httpx import AsyncClient
+from textual.app import RenderResult
 from textual.containers import VerticalScroll
 from textual.events import Event
 from textual.keys import Keys
+from textual.reactive import Reactive
+from textual.widget import Widget
 from textual.widgets import Select
 
 from txl.base import (
@@ -27,6 +30,33 @@
 ydocs = {ep.name: ep.load() for ep in entry_points(group="jupyter_ydoc")}
 
 
+class TopBar(Widget):
+    DEFAULT_CSS = """
+    TopBar {
+        dock: top;
+        width: 100%;
+        background: $foreground 5%;
+        text-align: right;
+        color: $text;
+        height: 1;
+    }
+    """
+    _busy_indicator = Reactive("○")
+    _busy = False
+
+    @property
+    def busy(self) -> bool:
+        return self._busy
+
+    @busy.setter
+    def busy(self, value: bool):
+        self._busy = value
+        self._busy_indicator = "◉" if value else "○"
+
+    def render(self) -> RenderResult:
+        return self._busy_indicator
+
+
 class NotebookEditorMeta(type(Editor), type(VerticalScroll)):
     pass
 
@@ -55,6 +85,11 @@ def __init__(
         self.edit_mode = False
         self.nb_change_target = asyncio.Queue()
         self.nb_change_events = asyncio.Queue()
+        self.top_bar = TopBar()
+        self.mount(self.top_bar)
+
+    async def watch_busy(self, event):
+        self.top_bar.busy = event.busy
 
     async def on_open(self, event: FileOpenEvent) -> None:
         await self.open(event.path)
@@ -123,6 +158,7 @@ def update(self):
             kernel_name = ipynb.get("metadata", {}).get("kernelspec", {}).get("name")
             if kernel_name:
                 self.kernel = self.kernels(kernel_name)
+                self.kernel.kernel.busy.connect(self.watch_busy)
         for i_cell in range(self.ynb.cell_number):
             cell = self.cell_factory(
                 self.ynb.ycells[i_cell], self.language, self.kernel
@@ -152,6 +188,7 @@ async def observe_nb_changes(self):
                         kernel_name = kernelspec.get("name")
                         if kernel_name:
                             self.kernel = self.kernels(kernel_name)
+                            self.kernel.kernel.busy.connect(self.watch_busy)
             elif target == "state":
                 if "dirty" in events.keys:
                     dirty = events.keys["dirty"]["newValue"]