UI freezes on screen dismissal with new Footer

[twrightsman]

I am getting a UI freeze after clicking the "Save" button in the following example code:

from textual import on
from textual.app import App, ComposeResult
from textual.containers import ScrollableContainer
from textual.screen import ModalScreen
from textual.widgets import Footer, Label, Button


class MyModal(ModalScreen[str | None]):
    BINDINGS = [("escape", "cancel", "Cancel")]

    def __init__(self, s: str):
        self._s = s
        super().__init__()

    def compose(self) -> ComposeResult:
        with ScrollableContainer():
            yield Label("My Screen")
            yield Button("Save", id="save", variant="success")
        yield Footer()

    @on(Button.Pressed, "#save")
    def handle_save(self) -> None:
        self.dismiss("Yes" if (self._s == "Hello!") else None)

    def action_cancel(self) -> None:
        self.dismiss(None)


class MyApp(App):
    BINDINGS = [
        ("m", "modal", "Show modal")
    ]

    def compose(self) -> ComposeResult:
        yield Footer()

    def action_modal(self) -> None:
        s = "Hello!"
        self.push_screen(MyModal(s))


if __name__ == "__main__":
    MyApp().run()

textual console shows:

[17:03:27] EVENT                                          message_pump.py:745
Unmount() >>> ScrollableContainer() method=<Widget.on_unmount>
─────────────────────────────────────────────────────────────────────────────
[17:03:30] WARNING                                            _callback.py:73
Callback functools.partial(<textual.await_remove.AwaitRemove object at 
0x7ff60c5be090>) is still pending after 3 seconds
[17:03:30] WARNING                                            _callback.py:73
Callback functools.partial(<bound method Widget.recompose of Footer()>) is 
still pending after 3 seconds

Using ClassicFooter does not cause the freeze.

Textual Diagnostics

Versions

Name	Value
Textual	0.63.3
Rich	13.7.1

Python

Name	Value
Version	3.11.2
Implementation	CPython
Compiler	GCC 12.2.0
Executable	/home/[snip]/.venv/bin/python

Operating System

Name	Value
System	Linux
Release	6.1.0-21-amd64
Version	#1 SMP PREEMPT_DYNAMIC Debian 6.1.90-1 (2024-05-03)

Terminal

Name	Value
Terminal Application	Unknown
TERM	foot
COLORTERM	truecolor
FORCE_COLOR	Not set
NO_COLOR	Not set

Rich Console options

Name	Value
size	width=212, height=46
legacy_windows	False
min_width	1
max_width	212
is_terminal	True
encoding	utf-8
max_height	46
justify	None
overflow	None
no_wrap	False
highlight	None
markup	None
height	None

[github-actions]

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[TomJGooding]

Try renaming your app to something like MyApp - do you see the same issues?

[twrightsman]

@TomJGooding Darn, that fixes this minimal example. But the issue remains in my actual app code. I'll try to make another minimal example that breaks.

[willmcgugan]

If you manage to reproduce it, can you try against main? There are some changes there that may be relevant.

[twrightsman]

I was mistaken earlier and forgot to go back to Footer instead of ClassicFooter. I just tested the example code above on my machine on 0.63.3 and master (5195a57) but unfortunately I can still reproduce the freeze when the save button is clicked.

[willmcgugan]

I can't seem to reproduce that on macOS. With main or the latest release. Can you reproduce it consistently, or is it intermitent?

[twrightsman]

I can reproduce it consistently. I'd say close to 80-90% of the time it triggers. With main, the textual console output is slightly different than 0.63.3:

[10:03:36] EVENT                                          message_pump.py:732
Unmount() >>> ScrollableContainer() method=<Widget.on_unmount>
─────────────────────────────────────────────────────────────────────────────
[10:03:39] WARNING                                            _callback.py:73
Callback functools.partial(<textual.await_remove.AwaitRemove object at 
0x7fb3a35ac290>) is still pending after 3 seconds
[10:03:39] WARNING                                            _callback.py:73
Callback functools.partial(<function 
Footer.on_mount.<locals>.bindings_changed at 0x7fb3a352b740>, MyModal()) is 
still pending after 3 seconds

[willmcgugan]

I can't reproduce this on Linux either. What terminal software are you running? Is this on a Raspberry Pi?

[twrightsman]

I am running foot; but I was just able to reproduce this in GNOME Terminal. I should have some time later to spin up a clean Debian VM and make sure it's not some strange environment configuration of mine.

[twrightsman]

Alright, it seems this only triggers when tabbing to the Save button and pressing enter to press it. I also do not see the behavior when clicking the button with the mouse. A friend was able to reproduce the freeze on MacOS as well when tabbing to the button and pressing enter.

[willmcgugan]

Thanks, I can reproduce it now.

[github-actions]

Don't forget to star the repository!

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[willmcgugan]

Please try 0.63.4

[twrightsman]

Seems to be fixed, thank you investigating!