Fix type hint aliasing for App under TYPE_CHECKING

Author: uriyyo

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 - Fix inability to copy text outside of an input/textarea when it was focused https://github.com/Textualize/textual/pull/6148
 - Fix issue when copying text after a double click https://github.com/Textualize/textual/pull/6148
+- Fixed type hint aliasing for App under TYPE_CHECKING. 
 
 ## [6.2.0] - 2025-09-30
 

src/textual/__init__.py

@@ -36,7 +36,7 @@
 if TYPE_CHECKING:
     from importlib.metadata import version
 
-    from textual.app import App
+    from textual.app import App as _App
 
     __version__ = version("textual")
     """The version of Textual."""
@@ -65,15 +65,15 @@ def __init__(
         log_callable: LogCallable | None,
         group: LogGroup = LogGroup.INFO,
         verbosity: LogVerbosity = LogVerbosity.NORMAL,
-        app: App | None = None,
+        app: _App | None = None,
     ) -> None:
         self._log = log_callable
         self._group = group
         self._verbosity = verbosity
         self._app = None if app is None else weakref.ref(app)
 
     @property
-    def app(self) -> App | None:
+    def app(self) -> _App | None:
         """The associated application, or `None` if there isn't one."""
         return None if self._app is None else self._app()