ThemeVariantScope doesn't refresh resources on first change of RequestedThemeVariant

[amwx]

Describe the bug

In my FluentAvalonia sample app, I have an option to toggle the theme for controls without changing the entire app theme. With the new ThemeVariant stuff, I've added a ThemeVariantScope control into the page to keep this behavior. When the theme toggle is requested the first time on the ThemeVariantScope, it doesn't tell the resources to refresh, and requires multiple attempts to get it to apply.

Video: (hopefully the clicking comes across) It takes 3 clicks to get the theme change to apply and then it works normally

Media1.mp4

• Version 11.0.999-cibuild0029462-beta

[maxkatz6]

Is it pushed to the branch? Theme switch works from the first change in the control catalog which makes it weird.
Only known issue so far was with popups inside of theme variant scope.

[amwx]

Is it pushed to the branch? Theme switch works from the first change in the control catalog which makes it weird. Only known issue so far was with popups inside of theme variant scope.

Not yet, I'm still cleaning up some of the old theme switch code but I'll try to push something out later this evening.

EDIT: Actually I can repro with this simple example in a new Avalonia project (with Avalonia.Themes.Fluent):

<Window>
    <ThemeVariantScope Name="ThemeScope">
		<Button Content="Click Me" />
	</ThemeVariantScope>
</Window>

var ts = this.FindControl<ThemeVariantScope>("ThemeScope");

KeyDown += (s, e) =>
{
    if (e.Key == Key.Space)
    {
        if (ts.ActualThemeVariant == ThemeVariant.Light)
        {
            ts.RequestedThemeVariant = ThemeVariant.Dark;
        }
        else
        {
            ts.RequestedThemeVariant = ThemeVariant.Light;
        }
    }
};

---

Edit again:
Adding NotifyChildResourcesChanged(new ResourcesChangedEventArgs()); after setting the RequestedThemeVariant gets it to apply on the first try, although this is on the window (since that's a protected method). Looking at the code, I can't find where the change of ActualThemeVariant triggers the resource invalidation (I don't see any property changed handlers for the property, except in TopLevel where it passes to PlatformImpl?.SetFrameThemeVariant)

[robloo]

There are a few instances I see where the theme variant isn't being applied correctly. For example, a popup isn't getting it set correctly. And even overlays that were hidden but then changed to visible keep the old theme variant. Doesnt relate exactly to this issue so just FYI. Seems to indicate invalidating is broken or the property isn't (re)applied on visibility changes.

[maxkatz6]

@amwx found the issue #10345