From b0656fd6062e46243b8d5584837e13b35e405a2c Mon Sep 17 00:00:00 2001
From: darrenburns <darrenburns@users.noreply.github.com>
Date: Thu, 30 Mar 2023 10:18:19 +0100
Subject: [PATCH] Some docstrings for actions (#2172)

---
 src/textual/app.py       | 18 ++++++++++++++++++
 src/textual/scrollbar.py |  4 ++++
 2 files changed, 22 insertions(+)

diff --git a/src/textual/app.py b/src/textual/app.py
index 52e631416..17c75ffb5 100644
--- a/src/textual/app.py
+++ b/src/textual/app.py
@@ -2375,18 +2375,36 @@ class App(Generic[ReturnType], DOMNode):
         self.pop_screen()
 
     async def action_back(self) -> None:
+        """Go back to the previous screen (pop the current screen)."""
         try:
             self.pop_screen()
         except ScreenStackError:
             pass
 
     async def action_add_class_(self, selector: str, class_name: str) -> None:
+        """Add a CSS class on the selected widget.
+
+        Args:
+            selector: Selects the widget to add the class to.
+            class_name: The class to add to the selected widget.
+        """
         self.screen.query(selector).add_class(class_name)
 
     async def action_remove_class_(self, selector: str, class_name: str) -> None:
+        """Remove a CSS class on the selected widget.
+
+        Args:
+            selector: Selects the widget to remove the class from.
+            class_name: The class to remove from  the selected widget."""
         self.screen.query(selector).remove_class(class_name)
 
     async def action_toggle_class(self, selector: str, class_name: str) -> None:
+        """Toggle a CSS class on the selected widget.
+
+        Args:
+            selector: Selects the widget to toggle the class on.
+            class_name: The class to toggle on the selected widget.
+        """
         self.screen.query(selector).toggle_class(class_name)
 
     def action_focus_next(self) -> None:
diff --git a/src/textual/scrollbar.py b/src/textual/scrollbar.py
index abb668bb4..1d590e2ed 100644
--- a/src/textual/scrollbar.py
+++ b/src/textual/scrollbar.py
@@ -298,17 +298,21 @@ class ScrollBar(Widget):
         self.mouse_over = False
 
     def action_scroll_down(self) -> None:
+        """Scroll vertical scrollbars down, horizontal scrollbars right."""
         if not self.grabbed:
             self.post_message(ScrollDown() if self.vertical else ScrollRight())
 
     def action_scroll_up(self) -> None:
+        """Scroll vertical scrollbars up, horizontal scrollbars left."""
         if not self.grabbed:
             self.post_message(ScrollUp() if self.vertical else ScrollLeft())
 
     def action_grab(self) -> None:
+        """Begin capturing the mouse cursor."""
         self.capture_mouse()
 
     def action_released(self) -> None:
+        """Finish capturing the mouse cursor"""
         self.capture_mouse(False)
 
     async def _on_mouse_up(self, event: events.MouseUp) -> None: