added quit_after

e2e_tests/test_apps/basic.py

@@ -177,7 +177,7 @@ class BasicApp(App, css_path="basic.css"):
 app = BasicApp()
 
 if __name__ == "__main__":
-    app.run()
+    app.run(quit_after=1)
 
     # from textual.geometry import Region
     # from textual.color import Color

src/textual/app.py

@@ -539,10 +539,20 @@ class App(Generic[ReturnType], DOMNode):
             keys, action, description, show=show, key_display=key_display
         )
 
-    def run(self) -> ReturnType | None:
+    def run(self, quit_after: float | None = None) -> ReturnType | None:
-        """The entry point to run a Textual app."""
+        """The main entry point for apps.
+
+        Args:
+            quit_after (float | None, optional): Quit after a given number of seconds, or None
+                to run forever. Defaults to None.
+
+        Returns:
+            ReturnType | None: _description_
+        """
 
         async def run_app() -> None:
+            if quit_after is not None:
+                self.set_timer(quit_after, self.shutdown)
             await self.process_messages()
 
         if _ASYNCIO_GET_EVENT_LOOP_IS_DEPRECATED:

src/textual/screen.py

@@ -53,6 +53,7 @@ class Screen(Widget):
 
     @property
     def is_current(self) -> bool:
+        """Check if this screen is current (i.e. visible to user)."""
         return self.app.screen is self
 
     @property