Handle parent/child binding conflicts in compound widget?

[TomJGooding]

Sorry if I have missed something in the docs or other discussions - but how might you handle parent/child binding conflicts in a compound widget (i.e. a custom widget composed of other child widgets)?

For example, in my custom widget below I want the down key to focus the overlay, so initially just set this to priority=True. But obviously the problem is that down now won't navigate the overlay. Presumably the binding instead needs to be set in the child widget, but then I'm not sure how to have this trigger an action in my compound widget...?

Hopefully this makes sense - thanks in advance for any advice!

from typing import Any, Generic, Iterable

from textual.app import App, ComposeResult, events
from textual.binding import Binding
from textual.containers import Vertical
from textual.widgets import Input
from textual.widgets._option_list import Option
from textual.widgets._select import SelectOverlay, SelectType


class AutoCompleteInput(Input):
    # BINDINGS = ???
    pass


class AutoComplete(Generic[SelectType], Vertical):
    BINDINGS = [Binding("down", "focus_overlay", show=False, priority=True)]
    # FIX: the down key obviously now won't navigate the overlay when focused

    DEFAULT_CSS = """
    AutoComplete {
        height: auto;
    }

    AutoComplete > SelectOverlay {
        width: 1fr;
        display: none;
        height: auto;
        max-height: 10;
        overlay: screen;
        constrain: y;
    }
    """

    def __init__(
        self,
        options: Iterable[tuple[str, SelectType]],
        *args: Any,
        **kwargs: Any,
    ):
        super().__init__(*args, **kwargs)
        self._initial_options = list(options)

    def compose(self) -> ComposeResult:
        yield AutoCompleteInput()
        yield SelectOverlay()

    def _on_mount(self, _: events.Mount) -> None:
        select_options: list[Option] = [
            Option(label) for label, _ in self._initial_options
        ]
        option_list = self.query_one(SelectOverlay)
        for option in select_options:
            option_list.add_option(option)

    def action_focus_overlay(self) -> None:
        overlay = self.query_one(SelectOverlay)
        overlay.display = True
        overlay.focus()
        overlay.select(0)


IMDB_TOP_10 = [
    "The Shawshank Redemption",
    "The Godfather",
    "The Dark Knight",
    "The Godfather Part II",
    "12 Angry Men",
    "Schindler's List",
    "The Lord of the Rings: The Return of the King",
    "Pulp Fiction",
    "The Lord of the Rings: The Fellowship of the Ring",
    "The Good, the Bad and the Ugly",
]


class AutoCompleteApp(App):
    def compose(self) -> ComposeResult:
        yield AutoComplete([(film, film) for film in IMDB_TOP_10])


if __name__ == "__main__":
    app = AutoCompleteApp()
    app.run()