Background refresh of a screen

[davep]

Writing this up as record of a conversation had with @willmcgugan yesterday, regarding if a screen that is "visible" in the ground of another screen (in other words when the foreground screen is transparent in areas) should be seen to update. So, given this code:

from datetime import datetime

from textual.app import App, ComposeResult, RenderResult
from textual.containers import Grid, Vertical
from textual.screen import ModalScreen
from textual.widgets import Label, Button

class PopUp(ModalScreen[None]):

    DEFAULT_CSS = """
    PopUp {
        align: center middle;
    }

    PopUp Vertical {
        align: center middle;
        background: $panel 50%;
        width: 30%;
        height: 30%;
        border: thick red;
    }
    """

    def compose(self) -> ComposeResult:
        with Vertical():
            yield Button("Press me to close me")

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

class Time(Label):

    DEFAULT_CSS = """
    Time {
        width: 1fr;
        height: 1fr;
        content-align: center middle;
        background: darkred;
        border: round red;
    }
    """

    def on_mount(self) -> None:
        self.auto_refresh = 0.2

    def render(self) -> RenderResult:
        return str(datetime.now())

class BackgroundRefreshApp(App[None]):

    CSS = """
    Grid {
        grid-size: 6;
    }
    """

    BINDINGS = [
        ("enter", "popup"),
    ]

    def compose(self) -> ComposeResult:
        with Grid():
            for _ in range(36):
                yield Time()

    def action_popup(self) -> None:
        self.push_screen(PopUp())

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

when you press Enter a modal popup will appear, and while it's visible none of the timers in the background will update. When hit again to dismiss the modal they'll start updating again.

It was suggested that they possibly should. It was my expectation that they wouldn't but I'm recording it here just in case.

Screen.Recording.2023-08-03.at.15.02.11.mov

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