add get_content_width

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## Unreleased 
+
+### Fixed
+
+- Fixed auto width not working for option lists https://github.com/Textualize/textual/pull/4507
+
 ## [0.59.0] - 2024-05-11
 
 ### Fixed

src/textual/widgets/_option_list.py

@@ -10,6 +10,7 @@
 from typing import ClassVar, Iterable, NamedTuple
 
 from rich.console import RenderableType
+from rich.measure import Measurement
 from rich.padding import Padding
 from rich.repr import Result
 from rich.rule import Rule
@@ -360,6 +361,15 @@ def __init__(
         # the state of the option list in regard to its available options.
         self.action_first()
 
+    def get_content_width(self, container: Size, viewport: Size) -> int:
+        """Get maximum width of options."""
+        console = self.app.console
+        options = console.options
+        return max(
+            Measurement.get(console, options, option.prompt).maximum
+            for option in self._options
+        )
+
     def _request_content_tracking_refresh(
         self, rescroll_to_highlight: bool = False
     ) -> None: