OptionList sizing issue

[willmcgugan]

The OptionList delays it's size calculation, which means that this code breaks.

I think we can refactor it to calculate the virtual size without so many intermediate messages.

from textual.app import App, ComposeResult
from textual.widgets import OptionList, Label
from textual.containers import VerticalScroll
from textual.message import Message

class Wizard(App):

    def compose(self) -> ComposeResult:
        with VerticalScroll(id = "body") as scroller:
            scroller.can_focus = False
            self.body = scroller
            yield OptionList("yes","no")

    async def ask_yes_no(self):
        await self.body.mount_all([
            Label("some text"),
            query := OptionList("yes","no")
        ])
        query.focus()

    async def on_option_list_option_selected(self, message: OptionList.OptionSelected) -> None:
        await message.option_list.remove()
        await self.ask_yes_no()
        self.body.scroll_end(animate=False)

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

[darrenburns]

Confirmed this is still an issue.

To be clear the issue is when the you add a bunch of items using the code above (pressing enter), when the option list gets to the bottom of the screen it sometimes is scrolled partially out of bounds.