[Bug] Accent Color and System Theme changes are not updated in Packaged WPF apps

This could be similar to #143. But this is an entirely different case.

There was an attempt to remove the app.manifest requirement (previously a mandatory need to detect the OS version) in 2c27fba92296ff54bde425fb7d3bd1baa844eb86. Despite removing the app.manifest requirement the bug has occurred to me (and I do have app manifest)

When the app is executed as an unpackaged application, there are no problems with theme/accent changes. But when the same app is executed as a packaged (MSIX) application, the accent-color/system-theme changes are not perceived by the packaged application.

I can assure that this bug doesn’t happen when the app is unpackaged.

Workaround

I used Reflection to invoke this internal method This won’t work see https://github.com/Kinnara/ModernWpf/issues/175#issuecomment-701740907

private void ListenToSystemColorChanges()
{
    Type ColorsHelperType = Type.GetType("ModernWpf.ColorsHelper, ModernWpf");
    PropertyInfo CurrentProperty = ColorsHelperType.GetProperty("Current", BindingFlags.Static | BindingFlags.Public);
    object colorsHelperInstance = CurrentProperty.GetValue(null);
    MethodInfo ListenToSystemColorChangesMethod = ColorsHelperType.GetMethod("ListenToSystemColorChanges",
        BindingFlags.Instance | BindingFlags.NonPublic);
    ListenToSystemColorChangesMethod.Invoke(colorsHelperInstance, null);
}

[ShankarBUS]

Hey @Kinnara, a suggestion

While committing a fix regarding a issue, you can use the Fix\Fixed\Fixes #{issue-no} {Issue Title} format to automatically close those issues while committing.

It saves me a lot of time. Would be helpful for you maintaining a repo efficiently

[Kinnara]

Yes, I’m fairly certain UISettings is the culprit, at least on Win10 2004. I tried ModernFlyouts and calling ListenToSystemColorChanges didn’t seem to help—the settings window still didn’t react to theme changes, for example.