WebView inside OptionContainer not resizing when maximising

[freakboy3742]

On Winforms, if you have a window that contains an OptionContainer, with a tab that contains a web content, and you resize the window, the web view responds. However, if you press the maximise button, the OptionContainer and Webvew don't resize to fit the window.

When you de-minimize, the OptionContainer resizes to fit the smaller window, but the WebView appears to be resized to fit the old, maximized size.

Example:

import toga
from toga.style import Pack
from toga.constants import COLUMN


class BugReport(toga.App):
    def startup(self):
        self.main_box = toga.Box(style=Pack(direction=COLUMN, flex=1))

        self.optioncontainer = toga.OptionContainer(style=Pack(flex=1))
        self.optioncontainer.add("A Tab", toga.WebView(url="https://beeware.org"))
        self.main_box.add(self.optioncontainer)

        self.main_window = toga.MainWindow(
            title=self.formal_name, size=(510, 600), position=(100, 0)
        )
        self.main_window.content = self.main_box
        self.main_window.show()


def main():
    return BugReport("Bug report", "org.beeware.bug")


if __name__ == "__main__":
    main().main_loop()

The resize works as expected on Cocoa and GTK.

Discussed in #1967

^{Originally posted by YTLoudYN June 8, 2023}
https://github.com/beeware/toga/assets/131869902/b6d49a5f-28be-4365-8e9c-abb87af18ed2