fix for removing

src/textual/message_pump.py

@@ -87,7 +87,7 @@ class MessagePump(metaclass=MessagePumpMeta):
         self._disabled_messages: set[type[Message]] = set()
         self._pending_message: Message | None = None
         self._task: Task | None = None
-        self._child_tasks: WeakSet[Task] = WeakSet()
+        self._timers: WeakSet[Timer] = WeakSet()
 
     @property
     def task(self) -> Task:
@@ -130,6 +130,10 @@ class MessagePump(metaclass=MessagePumpMeta):
         """
         self._parent = parent
 
+    def _detach(self) -> None:
+        """Set the parent to None to remove the node from the tree."""
+        self._parent = None
+
     def check_message_enabled(self, message: Message) -> bool:
         return type(message) not in self._disabled_messages
 
@@ -199,7 +203,8 @@ class MessagePump(metaclass=MessagePumpMeta):
             repeat=0,
             pause=pause,
         )
-        self._child_tasks.add(timer.start())
+        timer.start()
+        self._timers.add(timer)
         return timer
 
     def set_interval(
@@ -220,7 +225,8 @@ class MessagePump(metaclass=MessagePumpMeta):
             repeat=repeat or None,
             pause=pause,
         )
-        self._child_tasks.add(timer.start())
+        timer.start()
+        self._timers.add(timer)
         return timer
 
     def call_later(self, callback: Callable, *args, **kwargs) -> None:
@@ -248,13 +254,11 @@ class MessagePump(metaclass=MessagePumpMeta):
         if self._closed or self._closing:
             return
         self._closing = True
+        for timer in self._timers:
+            await timer.stop()
+        self._timers.clear()
         await self._message_queue.put(MessagePriority(None))
-        cancel_tasks = list(self._child_tasks)
-        for task in cancel_tasks:
-            task.cancel()
-        for task in cancel_tasks:
-            await task
-        self._child_tasks.clear()
+
         if self._task is not None and asyncio.current_task() != self._task:
             # Ensure everything is closed before returning
             await self._task
@@ -265,11 +269,13 @@ class MessagePump(metaclass=MessagePumpMeta):
     async def process_messages(self) -> None:
         self._running = True
         try:
-            return await self._process_messages()
+            await self._process_messages()
         except CancelledError:
             pass
         finally:
             self._running = False
+            for timer in self._timers:
+                await timer.stop()
 
     async def _process_messages(self) -> None:
         """Process messages until the queue is closed."""