fix selection disappearing

CHANGELOG.md

@@ -5,6 +5,13 @@ 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/).
 
+
+## [8.2.1] - 2026-03-29
+
+### Fixed
+
+- Fix crash when a widget disapears between selections https://github.com/Textualize/textual/pull/6455
+
 ## [8.2.0] - 2026-03-27
 
 ### Added 
@@ -3395,6 +3402,8 @@ 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
 
+[8.2.1]: https://github.com/Textualize/textual/compare/v8.2.0...v8.2.1
+[8.2.0]: https://github.com/Textualize/textual/compare/v8.1.1...v8.2.0
 [8.1.1]: https://github.com/Textualize/textual/compare/v8.1.0...v8.1.1
 [8.1.0]: https://github.com/Textualize/textual/compare/v8.0.2...v8.1.0
 [8.0.2]: https://github.com/Textualize/textual/compare/v8.0.1...v8.0.2

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "textual"
-version = "8.2.0"
+version = "8.2.1"
 homepage = "https://github.com/Textualize/textual"
 repository = "https://github.com/Textualize/textual"
 documentation = "https://textual.textualize.io/"

src/textual/screen.py

@@ -973,8 +973,12 @@ def get_selected_text(self) -> str | None:
 
         widget_text: list[str] = []
         for widget, selection in self.selections.items():
-            selected_text_in_widget = widget.get_selection(selection)
-            if selected_text_in_widget is not None:
+            # Filter out widgets that may have been removed since the text was selected
+            if (
+                widget.is_attached
+                and (selected_text_in_widget := widget.get_selection(selection))
+                is not None
+            ):
                 widget_text.extend(selected_text_in_widget)
 
         selected_text = "".join(widget_text).rstrip("\n")
@@ -2021,6 +2025,10 @@ def _watch__select_end(
         start_widget, screen_start, start_offset = self._select_start
         end_widget, screen_end, end_offset = select_end
 
+        if not start_widget.is_attached or not end_widget.is_attached:
+            # Widgets may have been removed since selection started
+            return
+
         if start_widget is end_widget:
             # Simplest case, selection starts and ends on the same widget
             if end_offset.transpose < start_offset.transpose:
@@ -2049,7 +2057,9 @@ def _watch__select_end(
             start_widget, end_widget = end_widget, start_widget
 
         # Get a widget which contains both widgets
-        container_widget = Widget.get_common_ancestor(start_widget, end_widget)
+        container_widget = Widget.get_common_ancestor(
+            start_widget, end_widget, default=self
+        )
 
         # Get a selection bounds shape
         selection_bounds = Shape.selection_bounds(

src/textual/widget.py

@@ -690,15 +690,18 @@ def text_selection(self) -> Selection | None:
         return self.screen.selections.get(self, None)
 
     @classmethod
-    def get_common_ancestor(cls, widget1: Widget, widget2: Widget) -> Widget:
+    def get_common_ancestor(
+        cls, widget1: Widget, widget2: Widget, *, default: Widget | None = None
+    ) -> Widget:
         """Get a common ancestors to both widgets.
 
         Raises:
-            ValueError: If there is not common ancestor (will not occur if both widgets are attached to the same DOM).
+            ValueError: If there is no common ancestor and `default` is not provided (will not occur if both widgets are attached to the same DOM).
 
         Args:
             widget1: A Widget.
             widget2: A second widgets.
+            default: A widget to return if no common ancestor is found.
 
         Returns:
             A common ancestor widgets.
@@ -709,6 +712,8 @@ def get_common_ancestor(cls, widget1: Widget, widget2: Widget) -> Widget:
             if node in ancestors2:
                 assert isinstance(node, Widget)
                 return node
+        if default is not None:
+            return default
         raise ValueError("No common ancestor found")
 
     def focus_on_click(self) -> bool:

tests/test_widget.py

@@ -23,6 +23,7 @@
     Log,
     OptionList,
     RichLog,
+    Static,
     Switch,
     TextArea,
 )
@@ -714,5 +715,54 @@ def compose(self) -> ComposeResult:
         label1 = app.query_one("#label1")
         label2 = app.query_one("#label2")
         label3 = app.query_one("#label3")
+
+        # Successful operations
         assert Widget.get_common_ancestor(label2, label3).id == "v4"
         assert Widget.get_common_ancestor(label2, label1).id == "v1"
+
+        with pytest.raises(ValueError):
+            # No common ancestor, throws a Value Error
+            Widget.get_common_ancestor(label1, Label("unattached"))
+
+        # No common ancestor with default
+        assert (
+            Widget.get_common_ancestor(label1, Label("unattached"), default=app.screen)
+            is app.screen
+        )
+
+
+async def test_select_remove():
+    """Test selecting text after a widget is removed.
+
+    Regression test for https://github.com/Textualize/textual/issues/6452
+
+    """
+
+    top_text = "Hello, World " * 20
+    vanish_text = "This will vanish " * 10
+
+    class SelApp(App):
+
+        BINDINGS = [("space", "vanish")]
+
+        def compose(self) -> ComposeResult:
+            yield Static(top_text)
+            yield Static(vanish_text, id="vanish")
+
+        def action_vanish(self) -> None:
+            self.query_one("#vanish").remove()
+
+    app = SelApp()
+    # Simulate mouse down, move to second widget, remove second widget, move mouse, mouse up
+    # Prior to the fix this would result in an error as the second widget was no longer attached
+    # Post fix, there should be no error, and the selected text should be from the first widget.
+    async with app.run_test() as pilot:
+        await pilot.mouse_down(offset=(5, 2))
+        await pilot.hover(offset=(20, 5))
+        await app.query_one("#vanish").remove()
+        await pilot.hover(offset=(25, 6))
+        await pilot.mouse_up(offset=(30, 5))
+        selected_text = app.screen.get_selected_text()
+        expected = ", World Hello, World Hello, World Hello, World Hello, World Hello, World Hello, World Hello, World "
+        print(repr(selected_text))
+        assert selected_text == expected