App does not close until mouse is moved when App.on_exit is async but does not await

[areslagae]

Hi all,

The app below does not close until the mouse is moved after clicking on close when CONFIRM_EXIT is False (macOS Tahoe 26.2, Python 3.14.5, Toga 0.5.4). In this case, the async method on_exit does not await.

To test click the close button not moving the mouse.

I am not sure if this is considered a usage error or a Toga error. Feel free to let me know so I can submit a bug report if needed.

import toga

class App(toga.App):

    def __init__(self):
        super().__init__(formal_name='formal_name', app_id='app_id')

    def startup(self):
        main_window = toga.MainWindow()
        main_window.show()
        self.main_window = main_window

    CONFIRM_EXIT = False
    
    async def on_exit(self) -> bool:
        result = True
        if self.CONFIRM_EXIT:
            result = await self.dialog(toga.QuestionDialog('Exit?', 'Exit?'))    
        return result

app = App()
app.main_loop()

[freakboy3742]

I think this is a manifestation of a current known bug - see #4394. There's a candidate fix associated with that issue - I need to investigate further to see if there is a better solution.