Use active message pump in pop screen (#3315)

* Use active message pump in pop screen

* message pump

CHANGELOG.md

@@ -25,6 +25,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 - Fixed a crash when removing an option from an `OptionList` while the mouse is hovering over the last option https://github.com/Textualize/textual/issues/3270
 - Fixed a crash in `MarkdownViewer` when clicking on a link that contains an anchor https://github.com/Textualize/textual/issues/3094
+- Fixed wrong message pump in pop_screen https://github.com/Textualize/textual/pull/3315
 
 ### Changed
 

src/textual/app.py

@@ -1783,9 +1783,11 @@ def push_screen(
             self.screen.post_message(events.ScreenSuspend())
             self.screen.refresh()
         next_screen, await_mount = self._get_screen(screen)
-        next_screen._push_result_callback(
-            self.screen if self._screen_stack else None, callback
-        )
+        try:
+            message_pump = active_message_pump.get()
+        except LookupError:
+            message_pump = self.app
+        next_screen._push_result_callback(message_pump, callback)
         self._load_screen_css(next_screen)
         self._screen_stack.append(next_screen)
         self.stylesheet.update(next_screen)

src/textual/screen.py

@@ -72,7 +72,7 @@ class ResultCallback(Generic[ScreenResultType]):
 
     def __init__(
         self,
-        requester: Widget | None,
+        requester: MessagePump,
         callback: ScreenResultCallbackType[ScreenResultType] | None,
     ) -> None:
         """Initialise the result callback object.
@@ -81,7 +81,7 @@ def __init__(
             requester: The object making a request for the callback.
             callback: The callback function.
         """
-        self.requester: Widget | None = requester
+        self.requester = requester
         """The object in the DOM that requested the callback."""
         self.callback: ScreenResultCallbackType | None = callback
         """The callback function."""
@@ -685,7 +685,7 @@ def _invoke_later(self, callback: CallbackType, sender: MessagePump) -> None:
 
     def _push_result_callback(
         self,
-        requester: Widget | None,
+        requester: MessagePump,
         callback: ScreenResultCallbackType[ScreenResultType] | None,
     ) -> None:
         """Add a result callback to the screen.