Stop OptionList.OptionHighlighted leaking out of Select

CHANGELOG.md

@@ -29,6 +29,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Rename `CollapsibleTitle.action_toggle` to `action_toggle_collapsible` to fix clash with `DOMNode.action_toggle` https://github.com/Textualize/textual/pull/4221
 - Markdown component classes weren't refreshed when watching for CSS https://github.com/Textualize/textual/issues/3464
 - Rename `Switch.action_toggle` to `action_toggle_switch` to fix clash with `DOMNode.action_toggle` https://github.com/Textualize/textual/issues/4262
+- Fixed `OptionList.OptionHighlighted` leaking out of `Select` https://github.com/Textualize/textual/issues/4224
 
 ### Changed
 

src/textual/widgets/_select.py

@@ -95,6 +95,12 @@ def on_option_list_option_selected(self, event: OptionList.OptionSelected) -> No
         event.stop()
         self.post_message(self.UpdateSelection(event.option_index))
 
+    def on_option_list_option_highlighted(
+        self, event: OptionList.OptionHighlighted
+    ) -> None:
+        """Stop option list highlighted messages leaking."""
+        event.stop()
+
 
 class SelectCurrent(Horizontal):
     """Displays the currently selected option."""