force intial resize event

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Fixed
 
 - Fixed infinite loop in `Widget.anchor` https://github.com/Textualize/textual/pull/5290
+- Fixed delayed App Resize event https://github.com/Textualize/textual/pull/5296
 
 ## [0.87.1] - 2024-11-24
 

src/textual/app.py

@@ -3067,6 +3067,9 @@ async def invoke_ready_callback() -> None:
                 try:
                     try:
                         await self._dispatch_message(events.Compose())
+                        await self._dispatch_message(
+                            events.Resize.from_dimensions(self.size, None)
+                        )
                         default_screen = self.screen
                         self.stylesheet.apply(self)
                         await self._dispatch_message(events.Mount())

src/textual/drivers/linux_driver.py

@@ -216,8 +216,6 @@ def _stop_again(*_) -> None:
         loop = asyncio.get_running_loop()
 
         def send_size_event() -> None:
-            if self._in_band_window_resize:
-                return
             terminal_size = self._get_terminal_size()
             width, height = terminal_size
             textual_size = Size(width, height)
@@ -231,7 +229,8 @@ def send_size_event() -> None:
         self._writer_thread.start()
 
         def on_terminal_resize(signum, stack) -> None:
-            send_size_event()
+            if not self._in_band_window_resize:
+                send_size_event()
 
         signal.signal(signal.SIGWINCH, on_terminal_resize)