Consider a :loading pseudo class

[davep]

It's not uncommon to have an array of widgets where, say, the border is used to help emphasise where focus is, for example:

from textual.app import App, ComposeResult
from textual.containers import Grid, Container

class BusyBox(Container, can_focus=True):

    DEFAULT_CSS = """
    BusyBox {
        border: panel red;
    }
    BusyBox:focus {
        border: panel green;
    }
    """

    def __init__(self, number: int) -> None:
        super().__init__()
        self.border_title = f"Busy box {number}"
        self.loading = bool(number % 3)

class LoadingApp(App[None]):

    CSS = """
    Grid {
        grid-size: 4;
    }
    """

    def compose(self) -> ComposeResult:
        with Grid():
            for n in range(16):
                yield BusyBox(n)

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

I feel it would be very useful if it were possible to also style a widget that is in the loading state. While it's true that a class could be applied when the loading value is set to True, and removed when set to False, allowing it to be done fully in CSS would mean there's no need to manage multiple locations where such changes could be made on a widget. Likewise, while this could be managed by the developer with a watch on loading, that then would generally require subclassing of all widgets that need this functionality; a pure-CSS solution would mean that a couple of rules could handle all sorts of widgets.

[willmcgugan]

I'm going to say no for now. Just because I don't want to keep adding to the very growing list of pseudo classes.

Happy to reconsider if we are asked for it.

[github-actions]

Don't forget to star the repository!

Follow @textualizeio for Textual updates.