add mouse down handler (#3778)

* add mouse down handler

* changelog

* version bump

Author: willmcgugan

CHANGELOG.md

@@ -5,6 +5,11 @@ 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/).
 
+## [0.43.1] - 2023-11-29
+
+### Fixed
+
+- Fixed clicking on scrollbar moves TextArea cursor https://github.com/Textualize/textual/issues/3763
 
 ## [0.43.0] - 2023-11-28
 
@@ -1460,6 +1465,7 @@ https://textual.textualize.io/blog/2022/11/08/version-040/#version-040
 - New handler system for messages that doesn't require inheritance
 - Improved traceback handling
 
+[0.43.1]: https://github.com/Textualize/textual/compare/v0.43.0...v0.43.1
 [0.43.0]: https://github.com/Textualize/textual/compare/v0.42.0...v0.43.0
 [0.42.0]: https://github.com/Textualize/textual/compare/v0.41.0...v0.42.0
 [0.41.0]: https://github.com/Textualize/textual/compare/v0.40.0...v0.41.0

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "textual"
-version = "0.43.0"
+version = "0.43.1"
 homepage = "https://github.com/Textualize/textual"
 repository = "https://github.com/Textualize/textual"
 documentation = "https://textual.textualize.io/"

src/textual/scrollbar.py

@@ -316,6 +316,10 @@ def action_grab(self) -> None:
         """Begin capturing the mouse cursor."""
         self.capture_mouse()
 
+    async def _on_mouse_down(self, event: events.MouseDown) -> None:
+        # We don't want mouse events on the scrollbar bubbling
+        event.stop()
+
     async def _on_mouse_up(self, event: events.MouseUp) -> None:
         if self.grabbed:
             self.release_mouse()