docstrings

src/textual/app.py

@@ -240,6 +240,11 @@ class App(DOMNode):
                 self.view.refresh(layout=True)
 
     def update_styles(self) -> None:
+        """Request update of styles.
+
+        Should be called whenever CSS classes / pseudo classes change.
+
+        """
         self.post_message_no_wait(messages.RefreshStyles(self))
 
     def mount(self, *anon_widgets: Widget, **widgets: Widget) -> None:

src/textual/css/model.py

@@ -65,6 +65,11 @@ class Selector:
         }
 
     def _add_pseudo_class(self, pseudo_class: str) -> None:
+        """Adds a pseudo class and updates specificity.
+
+        Args:
+            pseudo_class (str): Name of pseudo class.
+        """
         self.pseudo_classes.append(pseudo_class)
         specificity1, specificity2, specificity3 = self.specificity
         self.specificity = (specificity1, specificity2 + 1, specificity3)

src/textual/dom.py

@@ -188,6 +188,11 @@ class DOMNode(MessagePump):
         return tree
 
     def get_pseudo_classes(self) -> Iterable[str]:
+        """Get any pseudo classes applicable to this Node, e.g. hover, focus.
+
+        Returns:
+            Iterable[str]: Iterable of strings, such as a generator.
+        """
         return ()
 
     def reset_styles(self) -> None:

src/textual/widget.py

@@ -103,8 +103,10 @@ class Widget(DOMNode):
         return renderable
 
     def get_pseudo_classes(self) -> Iterable[str]:
+        """Pseudo classes for a widget"""
         if self._mouse_over:
             yield "hover"
+        # TODO: focus
 
     def get_child_by_id(self, id: str) -> Widget:
         """Get a child with a given id.