Revert "Prevent reactive-watcher loop in Tabs / TabbedContent." (#2322)

* Revert "Prevent reactive-watcher loop in Tabs / TabbedContent. (#2305)"

This reverts commit 66a6448.

* fix stuck tab

* fix for stuck underline

* snpshot

Author: willmcgugan

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/).
 
+## [0.20.1] - 2023-04-18
+
+### Fix
+
+- New fix for stuck tabs underline https://github.com/Textualize/textual/issues/2229
+
 ## [0.20.0] - 2023-04-18
 
 ### Changed
@@ -32,7 +38,6 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Fix empty ListView preventing bindings from firing https://github.com/Textualize/textual/pull/2281
 - Fix `get_component_styles` returning incorrect values on first call when combined with pseudoclasses https://github.com/Textualize/textual/pull/2304
 - Fixed `active_message_pump.get` sometimes resulting in a `LookupError` https://github.com/Textualize/textual/issues/2301
-- Fixed issue arising when active tab was changed too quickly in succession https://github.com/Textualize/textual/pull/2305
 
 ## [0.19.1] - 2023-04-10
 
@@ -769,6 +774,7 @@ 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
 
+[0.20.1]: https://github.com/Textualize/textual/compare/v0.20.0...v0.20.1
 [0.20.0]: https://github.com/Textualize/textual/compare/v0.19.1...v0.20.0
 [0.19.1]: https://github.com/Textualize/textual/compare/v0.19.0...v0.19.1
 [0.19.0]: https://github.com/Textualize/textual/compare/v0.18.0...v0.19.0

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "textual"
-version = "0.20.0"
+version = "0.20.1"
 homepage = "https://github.com/Textualize/textual"
 description = "Modern Text User Interface framework"
 authors = ["Will McGugan <[email protected]>"]

src/textual/widgets/_tabbed_content.py

@@ -83,6 +83,9 @@ class TabbedContent(Widget):
     }
     """
 
+    active: reactive[str] = reactive("", init=False)
+    """The ID of the active tab, or empty string if none are active."""
+
     class TabActivated(Message):
         """Posted when the active tab changes."""
 
@@ -113,16 +116,21 @@ def __init__(self, *titles: TextType, initial: str = "") -> None:
         self._initial = initial
         super().__init__()
 
-    @property
-    def active(self) -> str:
-        """The ID of the active tab, or empty string if none are active."""
-        return self.get_child_by_type(Tabs).active
+    def validate_active(self, active: str) -> str:
+        """It doesn't make sense for `active` to be an empty string.
+
+        Args:
+            active: Attribute to be validated.
+
+        Returns:
+            Value of `active`.
 
-    @active.setter
-    def active(self, active: str) -> None:
+        Raises:
+            ValueError: If the active attribute is set to empty string.
+        """
         if not active:
             raise ValueError("'active' tab must not be empty string.")
-        self.get_child_by_type(Tabs).active = active
+        return active
 
     def compose(self) -> ComposeResult:
         """Compose the tabbed content."""
@@ -178,6 +186,7 @@ def _on_tabs_tab_activated(self, event: Tabs.TabActivated) -> None:
         switcher = self.get_child_by_type(ContentSwitcher)
         assert isinstance(event.tab, ContentTab)
         switcher.current = event.tab.id
+        self.active = event.tab.id
         self.post_message(
             TabbedContent.TabActivated(
                 tabbed_content=self,
@@ -188,3 +197,8 @@ def _on_tabs_tab_activated(self, event: Tabs.TabActivated) -> None:
     def _on_tabs_cleared(self, event: Tabs.Cleared) -> None:
         """All tabs were removed."""
         event.stop()
+
+    def watch_active(self, active: str) -> None:
+        """Switch tabs when the active attributes changes."""
+        with self.prevent(Tabs.TabActivated):
+            self.get_child_by_type(Tabs).active = active