skip if not mounted (#3847)

* skip if not mounted

* avoid refresh before  mount

* micro op

* ws

Author: willmcgugan

src/textual/css/styles.py

@@ -713,13 +713,15 @@ def get_rule(self, rule: str, default: object = None) -> object:
     def refresh(
         self, *, layout: bool = False, children: bool = False, parent: bool = False
     ) -> None:
-        if parent and self.node and self.node.parent:
-            self.node.parent.refresh()
-        if self.node is not None:
-            self.node.refresh(layout=layout)
-            if children:
-                for child in self.node.walk_children(with_self=False, reverse=True):
-                    child.refresh(layout=layout)
+        node = self.node
+        if node is None or not node._is_mounted:
+            return
+        if parent and node._parent is not None:
+            node._parent.refresh()
+        node.refresh(layout=layout)
+        if children:
+            for child in node.walk_children(with_self=False, reverse=True):
+                child.refresh(layout=layout)
 
     def reset(self) -> None:
         """Reset the rules to initial state."""
@@ -757,11 +759,12 @@ def extract_rules(
             A list containing a tuple of <RULE NAME>, <SPECIFICITY> <RULE VALUE>.
         """
         is_important = self.important.__contains__
+        default_rules = 0 if is_default_rules else 1
         rules: list[tuple[str, Specificity6, Any]] = [
             (
                 rule_name,
                 (
-                    0 if is_default_rules else 1,
+                    default_rules,
                     1 if is_important(rule_name) else 0,
                     *specificity,
                     tie_breaker,

src/textual/css/stylesheet.py

@@ -448,7 +448,7 @@ def apply(
             for name in rules_map.keys() & node._selector_names
             for rule in rules_map[name]
         }
-        rules = [rule for rule in reversed(self.rules) if rule in limit_rules]
+        rules = list(filter(limit_rules.__contains__, reversed(self.rules)))
 
         # Collect the rules defined in the stylesheet
         node._has_hover_style = any("hover" in rule.pseudo_classes for rule in rules)

src/textual/widget.py

@@ -3121,6 +3121,8 @@ def refresh(
         Returns:
             The `Widget` instance.
         """
+        if not self._is_mounted:
+            return self
         if layout:
             self._layout_required = True
             self._stabilize_scrollbar = None