recompose

src/textual/app.py

@@ -2561,9 +2561,21 @@ class App(Generic[ReturnType], DOMNode):
 
         Recomposing will remove children and call `self.compose` again to remount.
         """
-        async with self.screen.batch():
-            await self.screen.query("*").exclude(".-textual-system").remove()
-            await self.screen.mount_all(compose(self))
+        # async with self.screen.batch():
+        #     await self.screen.query("*").exclude(".-textual-system").remove()
+        #     await self.screen.mount_all(compose(self))
+
+        children_by_id = {child.id: child for child in self.children if child.id}
+        new_children = []
+        for widget in compose(self):
+            if (
+                widget.id
+                and (existing_widget := children_by_id.get(widget.id)) is not None
+            ):
+                new_children.append(existing_widget)
+                existing_widget.set_reactive_state(widget.get_reactive_state())
+            else:
+                new_children.append(widget)
 
     def _register_child(
         self, parent: DOMNode, child: Widget, before: int | None, after: int | None

src/textual/dom.py

@@ -284,6 +284,27 @@ class DOMNode(MessagePump):
             self.call_later(self._initialize_data_bind)
         return self
 
+    def get_reactive_state(self) -> dict[str, object]:
+        """Get a dict of reactives and their values.
+
+        Returns:
+            A dict of reactives.
+        """
+        state = {name: getattr(self, name) for name in self._reactives}
+        return state
+
+    def set_reactive_state(self, state: dict[str, object]) -> None:
+        """Set reactives from a state dictionary.
+
+        Args:
+            state: A dict of reactive attributes.
+        """
+        for name in self._reactives:
+            try:
+                setattr(self, name, state[name])
+            except KeyError:
+                pass
+
     def _initialize_data_bind(self) -> None:
         """initialize a data binding.