MenuFlyoutItem text doesn't sync with system theme.

[Pdawg-bytes]

Describe the bug

In the latest WinUI 3 1.4 preview 1 build, MenuFlyoutItems Text theme doesn't update when the system theme is changed. I have a MenuFlyout in my Grid.Resources which I open using the RightTapped event of a button. If this menu isn't opened when I change the system theme, the background of the flyout is set properly, but the text color is not. If I switch from light mode to dark mode while this menu is closed, the text stays black. It only updates properly if the flyout is actually open when I change the system theme.

Steps to reproduce the bug

1. Create a MenuFlyout in your Grid.Resources
2. Open this menu, then close it.
3. While the menu is closed, change your system theme in Settings.
4. Notice how the text color is not changed to the correct color.

Expected behavior

I expected the text color to update whenever I change my system theme, regardless of its visibility.

Screenshots

(Yes, there is text here!)

Here's the bug in dark mode:

NuGet package version

WinUI 3 - Windows App SDK 1.4 Preview 1: 1.4.230628000-preview1

Windows version

Windows Insider Build (xxxxx)

Additional context

Windows 11 canary, 25905.1000.

[ynborokh]

I also observe similar issues with theme switching for flyouts. I use the following workaround to make it work (I switch the theme manually):

public YourControlWithFlyoutMenu()
{
    ...
    ActualThemeChanged += (_, _) => ActualizeRootTheme();
    ActualizeRootTheme();
}

private void ActualizeRootTheme()
{
    root.RequestedTheme = Application.Current.RequestedTheme == ApplicationTheme.Light
        ? ElementTheme.Light
        : ElementTheme.Dark;
}

Here, YourControlWithFlyoutMenu is the control where you call your flyout menu. root is the root element of the control's visual tree:

<UserControl x:Class="YourNamespace.YourControlWithFlyoutMenu" ...>
    <Grid x:Name="root ...>
        ...
    </Grid>
</UserControl>

Setting RequestedTheme directly on the control, instead of its root element, may also work (I don't remember details of why I'm stuck to root).

[Pdawg-bytes]

Thank you for the workaround! Hopefully it's fixed soon in the next few versions.

[AdriaanLarcai]

I posted an alternative workaround for this in #8756