text boxes never stop listening

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  • #1 by @CJstate — closed without merging

Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
88/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Active
Tech stack
python
Domain
cli

Research direction

Start with _text_area.py and _input.py at the cited _on_mount methods, then read Footer's unmount cleanup in _footer.py as a reference. Use the provided reproducer to check that removed Input and TextArea widgets are no longer retained without publishing the signal; done means the leak is fixed for both widgets.

Written by the indexing model from the issue text.

Description

The bug

TextArea._on_mount (_text_area.py:1904-1911) and Input._on_mount (_input.py:715-722) subscribe to self.screen.text_selection_started_signal with a callback that closes over self, and neither unsubscribes on unmount.
Signal keeps subscribers in a WeakKeyDictionary (signal.py:44), but the stored value is a wrapper holding that callback (signal.py:82-95), which holds self, so the weak key never dies. Dead subscribers are pruned only in publish() (signal.py:125-128), and nothing in Textual 8.2.8 publishes this signal. So every removed TextArea or Input stays alive, with its subtree, for the screen's lifetime.
Footer (_footer.py:333) and KeyPanel (_key_panel.py:182) already unsubscribe their own signal on unmount.

Example

import asyncio, gc
from textual.app import App
from textual.widgets import Input
async def main():
    app = App()
    async with app.run_test() as pilot:
        for _ in range(20):
            widget = Input()
            await app.mount(widget)
            await pilot.pause()
            await widget.remove()
            await pilot.pause()
        del widget
        gc.collect()
        print(sum(type(o) is Input for o in gc.get_objects()))  # 20, expected 0
asyncio.run(main())

One manual app.screen.text_selection_started_signal.publish(app.screen) drops it to 2. With TextArea in place of Input it stays at 20 until both a publish and an app theme change (the theme watcher is #6666).
Textual 8.2.8, Python 3.11.14, macOS.

Suggested fix

In TextArea and Input, unsubscribe on unmount, as Footer does:

self.screen.text_selection_started_signal.unsubscribe(self)
Dominant language
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